Prioritize the repository name over URL when posting changes.

rbt post was assuming that the repository URL provided should take
precedence over the repository name. The problem is that Subversion can
be given a repository URL that it can use for communicating with the
repository, but that URL isn't necessarily the one we want for lookup.

The Subversion issue should be fixed separately, but it's safe to say
that the repository name is a better option if provided. We now use that
over the URL if we have it.

Fixes bug #3277.
Reviewed at https://reviews.reviewboard.org/r/5960/
Change the branch information for release-0.6.x in .reviewboardrc.
Merge branch 'release-0.6.x'
Add all recent contributors to the AUTHORS list.
Bring over a better UnitTest class from Review Board.

This class lets us have docstrings that wrap lines for the unit test
summaries, instead of constraining them to a single line.

This does somewhat duplicate the purpose of RBTestBase in
rbtools/utils/, but that should maybe be split up into a set of mixins
or a new class, as that's really more for client tests and not that
useful for API tests.

Reviewed at https://reviews.reviewboard.org/r/5962/
Fix compatibility issues with older versions of Review Board.

Versions prior to 1.7.8 didn't have a 'url' field, causing
the 'absolute_url' property to fail at generated a suitable URL. We now
have a custom 'url' property on ReviewRequestResource that provides a
suitable default, just like 'absolute_url' does.

Likewise, versions of Review Board prior to 1.7.19 didn't have a
'mirror_path' field on the Repository resource, which broke a lookup. We
now conditionally get the 'mirror_path' instead of assuming it's there.
This is done instead of providing a custom property, in order to prevent
the resource from being misleading (since we can't generate any sane
default there).

Fixes bug #3348
Reviewed at https://reviews.reviewboard.org/r/5963/
Release RBTools 0.6.1.
Merge branch 'release-0.6.x'
Bump to 0.6.2 dev.
Merge branch 'release-0.6.x'