Refactor localization

* RTRC has been registered in Intuition and translations
  are now managed by translatewiki.net
  See also Krinkle/TsIntuition@aef8f24.

* Migrated from the old I18N.php at Toolserver to the Intuition
  API installed in Tool Labs (fixes #4).

* Depending on mediawiki.jqueryMsg, so that MediaWiki messages
  like "contributions" get {{GENDER:}} parsed properly (fixes #8)
Add package.json devDependencies for grunt-contrib-watch

Was previously missing causing an error when running `grunt watch`.