[devel at bb.net] Mergeable Buildbot pull requests

[dustin at buildbot.net]

Mergeable pull requests:

https://github.com/buildbot/buildbot/pull/2483 - TxRequestResponseWrapper has a 'code' property
https://github.com/buildbot/buildbot/pull/2481 - add qtile theme files to sdist
https://github.com/buildbot/buildbot/pull/2480 - Document how to get the build status as string via template context extension