Common database for content translation and APIs

* SQL scripts to build a new database for content translation, which is
  common for all wikis
* Table maps translations again the global user id provided by centralauth
  extension
* Translator-Translation relatonship is many:many
* Provides API for listing all translations of a given user.
  Example: api.php?action=query&list=contenttranslation&user=Santhosh
* Whenever article is publised an entry is inserted in the translations table
  and maps that translation to the current translator
* Extension started using namespaces

Change-Id: I0c0a9eb70c8ca143d30c0db5571c48deb12e2c16