Create module skeleton

Create clean_up{,_process,_database,_filesystem} functions on runbot.repo
Add test skeletons

Create Setup and TearDown
Add skeleton tests for Create clean_up{_process,_database,_filesystem}
Implement cleanup

On database init, mark all builds as done for deletion by the cron

clean_up marks all files in build directory as patterns to be cleaned unless
the build is not done
Implemented clean_up_filesystem method and its test
Implemented clean_up_database method and its test
Implemented clean_up_process method and its test

Add clean_up_pids method which kills done pids
Make sure runbut/static exists
Fix case when the build directory doesn't exist yet
Adding logging
Put cleanups in try blocks
Relax janitor a little, don't mark builds as done if no pids
Don't delete logs
fix premature exit of cleanup_pids

os.kill can raise OSError if given a PID which belongs to
another user. This can happen if we found an old PID in the database
for a process which exited, and the PID was recycled by the
operating system
fix logging calls

don't use the % operator in there, the logging module
takes care of doing parameter substitutions IFF the loglevel requires it.
improve error log messages
log marking builds as done
only select build which are not done at init
only mark old builds as done

we let builds which were not updated in the last 24 hours live
this prevents each odoo worker process to kill every build at startup
fix cleanup_filesystem
Fix missing colon