Launchpad automatic translations update.
[FIX] ir, ir_translation: it was not possible to empty the source of a translation, or this is sometime something that we want
[MERGE] Forward-port of latest 7.0 bugfixes, up to rev. 5139 rev-id: dle@openerp.com-20131121132305-qjlclgz5v9tze1fr