central: Add basic buildbot integration that creates a build request in a try jobdir.
central: Add missing arguments in the build request file.
buildbot: Add PR builders. This config is starting to be horrible and messy, needs a rewrite soon.
central: Provide branchname and shortrev properties to the buildbot (required by the current master config).
central: Remove spurious logging statement.
central/buildbot: support reporting pull request build status to GitHub
central: fix inverted conditions on matched github PR actions triggering rebuilds