(WIP) Studio: Adds Language Selection Menu

This works adds a language selection menu to a user's dashboard (per UI/feature request found here - https://edx-wiki.atlassian.net/wiki/pages/viewpage.action?pageId=48726317).

Status: The static assets and styles have been added, but JavaScript to manage the status/editing states as well as submit the form and save the user setting are still needed.
@andy-armstrong heads up that this form is necessary for Django i18n support -- that's the magic refreshing that enables the translation on the page.

See https://docs.djangoproject.com/en/1.4/topics/i18n/translation/ ; https://github.com/edx/edx-platform/blob/master/lms/templates/modal/_modal-settings-language.html#L29