Publications are now translatable

Added test to routing for it even though the routes were already localized (I think to support the locale specific indexes introduced in #293).
Publications/show view gets some t(...) calls
404 any requests for documents in a locale they are not translated into
Provide translation for attachments and doc header page text
Regenerate locale yml files to have keys for new translations
Add enough fr translations for the tests to pass
Merge branch 'translatable-publications'

Tracker: https://www.pivotaltracker.com/story/show/44080619