Update flask to 0.12.2

[pyup-bot]

There's a new version of Flask available.
You are currently using 0.12. I have updated it to 0.12.2

These links might come in handy: PyPI | Changelog | Repo

Changelog

0.12.2

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Released on May 16 2017

• Fix a bug in safe_join on Windows.

0.12.1

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Bugfix release, released on March 31st 2017

• Prevent flask run from showing a NoAppException when an ImportError occurs
  within the imported application module.
• Fix encoding behavior of app.config.from_pyfile for Python 3. Fix
  2118.
• Use the SERVER_NAME config if it is present as default values for
  app.run. 2109, 2152
• Call ctx.auto_pop with the exception object instead of None, in the
  event that a BaseException such as KeyboardInterrupt is raised in a
  request handler.

Got merge conflicts? Close this PR and delete the branch. I'll create a new PR for you.

Happy merging! 🤖

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This change is