Switch to the new centralized templates for admin form pages.

Review Request #7852 — Created Jan. 7, 2016 and submitted — Latest diff uploaded

Information

Review Board
release-2.6.x

Reviewers

Djblets has a new set of common admin form templates meant to replace
the usage of the siteconfig-hosted templates. This doesn't impact Review
Board much, but we do make use of some now-deprecated templates. This
switches over to using the new ones where appropriate.

Tested each of the affected pages.