Upgrade itsdangerous to 1.1.0 (fixes #5)

itsdangerous in version 1.0.0 has been pulled
from PyPI, which lets dependeny resolution fail.

https://palletsprojects.com/blog/itsdangerous-1-1-0-released/

Library authors do not expected incompatible
changes.

Pipfile.lock

@@ -33,7 +33,6 @@
                 "sha256:2335065e6395b9e67ca716de5f7526736bfa6ceead690adf616d925bdc622b13",
                 "sha256:5b94b49521f6456670fdb30cd82a4eca9412788a93fa6dd6df72c94d5a8ff2d7"
             ],
-            "markers": "python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version != '3.2.*' and python_version != '3.3.*'",
             "version": "==7.0"
         },
         "flask": {
@@ -53,11 +52,10 @@
         },
         "itsdangerous": {
             "hashes": [
-                "sha256:a7de3201740a857380421ef286166134e10fe58846bcefbc9d6424a69a0b99ec",
+                "sha256:321b033d07f2a4136d3ec762eac9f16a10ccd60f53c0c91af90217ace7ba1f19",
-                "sha256:aca4fc561b7671115a2156f625f2eaa5e0e3527e0adf2870340e7968c0a81f85"
+                "sha256:b12271b2047cb23eeb98c8b5622e2e5c5e9abd9784a153e9d8ef9cb4dd09d749"
             ],
-            "markers": "python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version != '3.2.*' and python_version != '3.3.*'",
+            "version": "==1.1.0"
-            "version": "==1.0.0"
         },
         "jinja2": {
             "hashes": [
@@ -92,7 +90,6 @@
                 "sha256:41c3db2fc01e5b907288010dec72f9d0a74e37d6994e6eb56849f59fea2265ae",
                 "sha256:8819bba37a02d143296a4d032373c4dd4aca11f6d4c9973335ca75f9c8475f59"
             ],
-            "markers": "python_version != '3.2.*' and python_version != '3.3.*' and python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version < '4'",
             "version": "==1.24"
         },
         "werkzeug": {
@@ -116,7 +113,6 @@
                 "sha256:0312ad34fcad8fac3704d441f7b317e50af620823353ec657a53e981f92920c0",
                 "sha256:ec9ae8adaae229e4f8446952d204a3e4b5fdd2d099f9be3aaf556120135fb3ee"
             ],
-            "markers": "python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version != '3.2.*' and python_version != '3.3.*'",
             "version": "==1.2.1"
         },
         "attrs": {
@@ -168,7 +164,6 @@
                 "sha256:edabd457cd23a02965166026fd9bfd196f4324fe6032e866d0f3bd0301cd486f",
                 "sha256:fdf1c1dc5bafc32bc5d08b054f94d659422b05aba244d6be4ddc1c72d9aa70fb"
             ],
-            "markers": "python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version != '3.2.*' and python_version != '3.3.*'",
             "version": "==1.11.5"
         },
         "chardet": {
@@ -214,7 +209,6 @@
                 "sha256:f05a636b4564104120111800021a92e43397bc12a5c72fed7036be8556e0029e",
                 "sha256:f3f501f345f24383c0000395b26b726e46758b71393267aeae0bd36f8b3ade80"
             ],
-            "markers": "python_version != '3.2.*' and python_version != '3.0.*' and python_version != '3.1.*' and python_version < '4' and python_version >= '2.6'",
             "version": "==4.5.1"
         },
         "coveralls": {
@@ -247,6 +241,7 @@
                 "sha256:e79ab4485b99eacb2166f3212218dd858258f374855e1568f728462b0e6ee0d9",
                 "sha256:f995d3667301e1754c57b04e0bae6f0fa9d710697a9f8d6712e8cca02550910f"
             ],
+            "markers": "extra == 'secure'",
             "version": "==2.3.1"
         },
         "docopt": {
@@ -285,6 +280,7 @@
                 "sha256:64b28eec5e78e7510698f6d4da08800a5c575caa4a286c93d651c5d3ff7b6794",
                 "sha256:b146c751ea45cad6188dd6cf2d9b757f6f4f8d6ffb96a023e6f2e26eea02a72c"
             ],
+            "markers": "python_version < '3'",
             "version": "==1.0.22"
         },
         "more-itertools": {
@@ -308,7 +304,6 @@
                 "sha256:447ba94990e8014ee25ec853339faf7b0fc8050cdc3289d4d71f7f410fb90095",
                 "sha256:bde19360a8ec4dfd8a20dcb811780a30998101f078fc7ded6162f0076f50508f"
             ],
-            "markers": "python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version != '3.2.*' and python_version != '3.3.*'",
             "version": "==0.8.0"
         },
         "py": {
@@ -316,14 +311,12 @@
                 "sha256:bf92637198836372b520efcba9e020c330123be8ce527e535d185ed4b6f45694",
                 "sha256:e76826342cefe3c3d5f7e8ee4316b80d1dd8a300781612ddbc765c17ba25a6c6"
             ],
-            "markers": "python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version != '3.2.*' and python_version != '3.3.*'",
             "version": "==1.7.0"
         },
         "pycparser": {
             "hashes": [
                 "sha256:a988718abfad80b6b157acce7bf130a30876d27603738ac39f140993246b25b3"
             ],
-            "markers": "python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version != '3.2.*' and python_version != '3.3.*'",
             "version": "==2.19"
         },
         "pyopenssl": {
@@ -331,6 +324,7 @@
                 "sha256:26ff56a6b5ecaf3a2a59f132681e2a80afcc76b4f902f612f518f92c2a1bf854",
                 "sha256:6488f1423b00f73b7ad5167885312bb0ce410d3312eb212393795b53c8caa580"
             ],
+            "markers": "extra == 'secure'",
             "version": "==18.0.0"
         },
         "pytest": {
@@ -386,7 +380,6 @@
                 "sha256:41c3db2fc01e5b907288010dec72f9d0a74e37d6994e6eb56849f59fea2265ae",
                 "sha256:8819bba37a02d143296a4d032373c4dd4aca11f6d4c9973335ca75f9c8475f59"
             ],
-            "markers": "python_version != '3.2.*' and python_version != '3.3.*' and python_version >= '2.7' and python_version != '3.0.*' and python_version != '3.1.*' and python_version < '4'",
             "version": "==1.24"
         }
     }