Merge branch 'master' into develop
Bugfix in pb_base/handler/lock.py for a race condition in checking a lockfile.
Added CouldntOccupyLockfileError class (including necessary translations) into pb_base/errors.py
Integrated CouldntOccupyLockfileError in pb_base/handler/lock.py
Redesigned test/test_lock.py
Merge branch 'develop'
Version bump for mastering + dch