More chem tweaks
Start notifiers from the dev helper
Be explicit about commit/browse/reflog urls
Store a commit's status

- New when nothing is scheduled
- Fail if ainything has failed
- Success if all have succeeded
- In progress otherwise
Fix bugs in the mail notifier
Add a webinterface based on flask

Design and implementation ideas stolen from goblet :)
Run checkout and its hooks under the same lock
Give golem's screen a name
Create pidfiles for easy killing
Start notifiers too
Job-logging improvements: log commands and use the logging framework properly
Better JSON serialization
Misc. bugfixes
Bugfixes related to retrying
Work around MySQL autoclosing idle connections