"node: language" sort criteria doesn't work

Hello!

In a view's search criteria dropdown a "Node: language" option provided by localizer was not showing, instead there were a blank line.
This is due to the field name ("language") and sorts array key ("name") were swapped:

     "sorts" => array(
-      "name" => array('language' => "Node : Language")
-    ),
+      "language" => array(
+      	'name' => t("Node: Language"),
+      	'help' => t('This will sort by language.')
+      )
+    ),    

Also in this patch:

• new "Language code only" option to display short language code, i.e. "en" or "ru"; this is handy for use with services so that remote app can use short and convenient codes instead of full language name
• exposed strings (fields, filters, etc.) wrapped in t() call; we are into localization after all, don't we? :)
• just a cleanup: get rid of duplicating code in views_handler_localizer_language()

Hope it helps.