Buildr config to consolidate all translations under common.

The XNap I18n library we are using makes it impossible to chain
ResourceBundles in a parent-child relationship.  Each I18n object can
only point to one ResourceBundle.  Rather than attempt to reimplement
the I18n functionality, we will conform to XNap's expectation of a
single ResourceBundle by putting all the strings into a keys file under
common.
Move all current translations to common.
Merge all PO and POT files and place under common.