Fixed error output on rbt setup-repo when writing .reviewboardrc fails.

This is a trivial fix to include both formatting arguments when
displaying an error after failing to write .reviewboardrc. Previously,
the arguments weren't wrapped in a tuple.
Release RBTools 0.5.4.
Merge branch 'release-0.5.x'
Allow for using repository names with Subversion repositories in 0.5.x.

Repository names for Subversion repositories broke Subversion. On
0.5.x, the name is stuffed into the repository_url setting, which the
Subversion code assumes means we're operating on some possibly remote
repository.

The proper fix to separate out repository names and URLs is coming in
0.6, but for now, we check the repository_url whenever we use it to see
whether it's a URL or a name.

This is intended to stay only on the 0.5.x branch, and will not merge to
master.
Add --svn-show-copies-as-adds to post-review.

This option was added to rbt post but not post-review, but unfortunately the
backend didn't know that. There's no reason to not have it in post-review, for
people who still need to use that for some reason or other.
Release RBTools 0.5.5.
Merge branch 'release-0.5.x'
Merge branch 'release-0.5.x'
Fix the link to the 0.5.5 release notes.
Merge branch 'release-0.5.x'
Support parent diffs with Mercurial

This patch adds support for parent diffs to Mercurial when specifying specific
revisions. If the base revision is not included in the remote, a relevant
parent diff will be automatically determined.

This does not yet support using the --parent-branch to specify a parent when
posting the current tip.

Testing Done:
Wrote some new tests. Executed tests locally and everything appears to work as
expected!

Bugs: 3067

Reviewed at https://reviews.reviewboard.org/r/5207/