Right now, the buildbot-related roles that we have (buildmaster, buildmaster-configure, buildslave, buildslave-configure) have some very taskotron-specific stuff in them. Other groups have been talking about using buildbot in infra and it would be nice if they could reuse the buildbot roles that we've written.

• extract the taskotron-specific stuff (eg. the artifacts config and dir creation in taskotron/buildmaster) into a standalone taskotron-specific role
• refactor the db creation bits to use a single set of vars instead of all the when: deployment_type == 'dev' stuff
• move the buildbot roles to a buildbot subdir of the roles in infra's repo, updating all the stuff that referred to the old paths