Fix a bad regression with the review group form.

Review Request #8430 — Created Sept. 24, 2016 and submitted — Latest diff uploaded

Information

Review Board
release-2.5.x
8da4f15...

Reviewers

Due to a quirk in the way forms are initialized, the review group form was
losing the "name" and "display name" fields before validation. This caused
saving new items to always fail.

Passing the local_site_name all the way through kwargs fixes the issue. I've
applied the same fix to the DefaultReviewerForm, and made both call the
superclass' clean method, just for completeness.

Was able to save new review groups and default reviewers.