Add exit_code field to the Build model. Also add corresponding south migration.
Store exit code of each build.
Display exit code next to a failed build.
Add single_version field to projects.models.
Add south migration for single_version field.
Handle single_version docs for '/docs/' URLs.

* Add SingleVersionMiddleware(), which handles '/docs/<project>/...' URLs.
* Add serve_single_version_docs() view function.
* Add new urlconf (single_version_urls.py)
* Doesn't yet handle subdomain URLs.
Add tests for SingleVersionMiddleware.

* Test '/docs/<project>' URLs only.
* Add "catchall" URL pattern so that CommonMiddleware doesn't
  append slash to valid single_version URLs like '/docs/pip/usage.html'.
* Revise tests that 404 directly now, rather than redirect and
  then 404.
Handle single_version docs for subdomains & CNAMEs.
Refactor SingleVersionMiddleware.
Add logging to SingleVersionMiddleware.
Don't blow up if single_version field is missing.
Update theme
Support dirhtml in the canonical snippet.
Update FAQ, though this will be a feature soon.
Well, that didn't work :)
Merge pull request #588 from Kami/include_status_code_on_failed_build

Display exit code on build details page for the failed builds
Merge pull request #591 from toffer/issue-293-single-version

Issue 293 single version
Add a start of canonical URL support.
Sneak language support into template context
Add link to contribution-guide.org /cc @bitprophet