(bug 48620) Enable Translate extension on Wikimedia Commons

This patch enables the Translate extension on Commons. In line
with the default settings, bureaucrats will be able to add and
remove users from the 'translationadmin' group. Since Commons
does not require so many translation states, we'll be using
Nike's suggestion from bug 41585 comment 3, including automatic
state changes.

Per bug 48620 comment 6, I'm also using this patch to enable
UniversalLanguageSelector, as it seems a dependency for this
extension.

Other configuration changes (enabling admins to add and remove
themselves from the abovementioned user group, enabling the
TranslateNotification extension) might follow soon upon
community request if need be.

Bug: 48620
Change-Id: I2a4b70a075dabe0489456db372a6ee40c9360c4d