Add the field mirror_path to RepositoryResource.

This adds the mirror_path field to RepositoryResource. This field
was previously not exposed in the API.

Reviewed at https://reviews.reviewboard.org/r/4897/
Fix a stray comma in RepositoryResource.

This comma was accidentally introduced in a recent change to
RepositoryResource, and broke things. It's now removed.
Fix displaying review requests for a group on a Local Site.

The page showing review requests for a group wasn't passing in the
Local Site, due to a recent change. This meant that those using Local
Sites would get a blank list of review requests when viewing a group.
Merge branch 'release-1.7.x'