Support for reconfiguration of the buildmaster without interrupting running builds. This has been working for a long time, but has some structural problems that probably need to be addressed a high level.
- buildbot.tac do not allow 'print <string>' lines anymore
- changes to slavebuilddir in a reconfig affect running builds
- reconfig by graceful failover
- Experiment with loading config in a "rollback importer"
- Schedulers should have names and reconfigService methods