Cleanup the UploadDiffForms

Review Request #9638 — Created Feb. 14, 2018 and submitted — Latest diff uploaded

Information

Review Board
release-4.0.x
5a32d89...

Reviewers

The diffviewer.forms.UploadDiffForm and reviews.forms.UploadDiffForm
were really out of date with current (Django 1.6) Django forms and our
documentation standards. The create() method on both was taking in
arguments that were already known by the form and did not verify that
the form was valid before attempting to create the models.

These issues have all been addressed and unit tests updated.

Ran unit tests.