Don't use unique_together in HostingServiceAccount.

The unique_together constraint broke several MySQL instances, due to the
combined key name length being too long when using UTF-8.

This particular index isn't that useful to us in practice, so nuke it
until we know more about why this fails.

Any existing tables that have this successfully added should continue to
be fine. Any new ones won't have it. Django-Evolution doesn't get
involved with unique_together, so there's no evolution to ship.
Improve i18n a bit.

I'm working on integrating the Italian localization that we recieved at
https://reviews.reviewboard.org/r/4298/

There are a few things that were getting in the way here. We have some old i18n
scripts in contrib/ which mostly work, but should be removed in favor of the
django-admin.py versions. The django-admin.py version of makemessages was
erroring out in a couple places where we were using positional format strings
with multiple arguments, instead of parameter names. I've fixed these up.

There are also several strings which aren't marked for translation. A lot of
these are likely coming from javascript, but one that was immediately obvious
was the dashboard's sidebar.

Testing done:
Integrated the contributed Italian localization files, and ran
compilemessages. Set my browser to prefer Italian, and saw that most of
the UI was now translated. Neat.

Reviewed at https://reviews.reviewboard.org/r/4426/
Make use of Beanstalk's new blob API for fetching files.

Beanstalk kindly added a blob API for us so that we could easily fetch
the contents of files without need the base_commit_id. That gives our
users the choice to continue using older versions of RBTools or to
upload a standard 'git diff' if they choose.

We now use the new blob API when fetching the raw contents of a file, or
when we need to check file existence without having a base_commit_id.

Unit tests were updated to handle the new flows, and to not expect
errors in the case of Git + no base commit ID.
Merge branch 'release-1.7.x'