Add localization tests #55
Description
Beside -testSelectiveUndo/RedoCommitDescriptor, we don't have tests to check the localization support built into COCommitDescriptor works properly.
To support testing this, we need a new method like +[COCommitDescriptor reloadCommitDescriptorsForPreferredLocalizations:] that could be called to switch the active language during some tests, and restore it back to NSBundle.developmentLocalization afterwards.