Fix Jenkins translation jobs

The jobs ceilometer-propose-translation-update and
ceilometer-upstream-translation-update do not update from
transifex since our po files contain duplicate entries where
obsolete entries duplicate normal entries.

Remove all obsolete entries to fix the jobs.

Add test to pep8 that checks that no new breakages get
introduced.

Change-Id: I3d7d04a7d5d073d5123f1f7b1e16fd3ef167acfb
Closes-Bug: #1299349
Merge "Fix Jenkins translation jobs"