Add a LocalSite-enabled feature checker

Review Request #8472 — Created Oct. 17, 2016 and submitted — Latest diff uploaded

Information

Review Board
release-3.0.x
499d182...

Reviewers

The LocalSiteFeatureChecker allows features to be enabled or disabled
at the LocalSite level. Features not configured on a LocalSite will
fall back to the global configuration (first site configuration, then
Django settings).

Additionally, the status update work has been reworked to provide the
necessary information (a LocalSite or a HttpRequest) to use the new
feature checker.

This feature checker is now the default for Review Board.

Ran unit tests.