Bump gallery picker version in 7.7 and 7.8 release poms

By HIPPLUG-696, the gallery picker 1.11.02 was released
7.8 and 7.7 release poms need to be bumped (trunk has 1.12.xx branch)

NB on 7.7, the WARN about hippo:version property (see http://www.onehippo.org/7_7/library/about/release-notes/release-notes-7.7.9.html) should not occur any more