Update flask-wtf to 0.14.2

[pyup-bot]

There's a new version of Flask-WTF available.
You are currently using 0.14. I have updated it to 0.14.2

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

Changelog

0.14.2

---

Released 2017-01-10

• Fix bug where FlaskForm assumed meta argument was not None if it
  was passed. (278_)

.. _278: wtforms/flask-wtf#278

0.14.1

---

Released 2017-01-10

• Fix bug where the file validators would incorrectly identify an empty file as
  valid data. (276, 277)

• FileField is no longer deprecated. The data is checked during
  processing and only set if it's a valid file.
• has_file is deprecated; it's now equivalent to bool(field.data).
• FileRequired and FileAllowed work with both the Flask-WTF and
  WTForms FileField classes.
• The Optional validator now works with FileField.

.. _276: wtforms/flask-wtf#276
.. _277: wtforms/flask-wtf#277

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

Happy merging! 🤖