Bump django dependency to 1.6

This change updates our django dependency to >= 1.6.1.

With the previous change to make sure that initialize() is called from test
setUp() methods, this is pretty small:
* Update the hg and bzr tests to properly detect missing dependencies and skip
  tests as appropriate.
* Remove the django.contrib.markup app. We got rid of our usage of this a while
  ago and forgot to remove it from INSTALLED_APPS. In Django 1.6 it's been
  removed entirely.
* Change the setup.py check to reject Python 2.6 versions less than 2.6.5.
* Fix call to compile_messages() in build-i18n.py

Testing done: Ran unit tests.

Reviewed at https://reviews.reviewboard.org/r/5310/
Simplify and fix static files serving.

Our urls were doing some backflips to be able to serve static files on
production environments when DEBUG=True, which conflicted with a change that
they made in django. We now serve static media only when DEBUG=True and
PRODUCTION=False, which means that we can use only
`django.contrib.staticfiles.views.serve`.

Testing done: Used the devserver.

Reviewed at https://reviews.reviewboard.org/r/5391/
Switch the "check updates required" middleware to use process_view.

The introduction of apply_to for media bundles was interfering with the updates
required middleware. In particular, what was happening was that we tried to
render a template from the process_request method of a middleware, which
happens before HttpRequest.resolver_match is set. This is easily fixed by using
process_view instead, which is probably more correct for this middleware anway.

This problem exhibited itself when running the
testManualUpdatesRequiredBadUpload unit test. I've checked all our other
middlewares to make sure that none of them are trying to render responses from
process_request.

Testing done: Ran unit tests.

Reviewed at https://reviews.reviewboard.org/r/5389/
Use 'cvs rls' to check repository existance rather than checking CVSROOT/modules.

The CVSROOT/modules file is not available on every CVS server, which makes it
impossible to add some repositories. This change fixes check_repository to use
'cvs rls' instead. If this command succeeds, we know that there's an accessible
cvs server at the given cvsroot.

Testing done: Added the cvs cvs to my local server.

Fixes bug 1986.

Reviewed at https://reviews.reviewboard.org/r/5392/
Fix Issue 3217: Remove download link for a "new version" of a deleted file.

We don't show the orig revision or a download link for it for new files, so we
probably shouldn't show the new revision or a download link for deleted files,
either.

Testing Done:
* Created a review with a deleted file.
* Download link for a new revision of a deleted file no longer appears in the
  file revision header.
* Headers for modified and new files remain unchanged.

Bugs closed: 3217

Reviewed at https://reviews.reviewboard.org/r/5377/
Advise using the Apache Prefork MPM instead of Worker.

The Worker MPM can cause problems because our code isn't designed to be
multi-threaded. Advise using the Prefork MPM in the docs.

Fixes (or at least works around) bug 2720.
Use Popen .communicate() instead of .stdin.write() to avoid deadlocks.

Writing to Popen.stdin can cause a deadlock if the passed-in data is larger
than the OS's buffer. The communicate() method avoids this problem, and it
makes the code a bit shorter, too.

Testing done:
* Ran unit tests.
* Smoke tested a few diffs.

Fixes bug 2247.

Reviewed at https://reviews.reviewboard.org/r/5393/
Sort the results in the user autocomplete better.

The results in the user autocomplete are basically in the order that they come
from the database. This is kind of crummy when there are multiple matches.

This change adds a sort comparison mechanism which will sort all username
matches ahead of real name matches. Within those categories, the names are
sorted in alphabetical order.

Testing done:
Added a bunch of users with usernames that started with a common substring, and
a bunch of users with first and last names that started with the same
substring. Saw that when I put that substring in the "People" field, the
autocomplete results put all the username matches first, and all the realname
matches after.

Fixes bug 2107.

Reviewed at https://reviews.reviewboard.org/r/5394/
Require Django Evolution 0.7.