Bump werkzeug from 0.10.1 to 0.15.3

Bumps [werkzeug](https://github.com/pallets/werkzeug) from 0.10.1 to 0.15.3.
- [Release notes](https://github.com/pallets/werkzeug/releases)
- [Changelog](https://github.com/pallets/werkzeug/blob/master/CHANGES.rst)
- [Commits](pallets/werkzeug@0.10.1...0.15.3)

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

requirements.txt

@@ -2,7 +2,7 @@ Flask==0.10.1
 Flask-PyMongo==0.3.0
 Jinja2==2.7.3
 MarkupSafe==0.23
-Werkzeug==0.10.1
+Werkzeug==0.15.3
 itsdangerous==0.24
 pymongo==2.8
 pytz==2014.10