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