Adding support to only show appropriate languages on supported services

This change introduces a dictionary which maps docs to languages. I'll make the list fully functional when we are confident in this approach.

Relevant changes are at https://github.com/rackerlabs/developer.rackspace.com/compare/dev...gh-206#diff-c669c82f2dfb340df8af5584cb9ad589R4

- Fixes #206
Probably not, but I had forgotten #226. I'll change this up to just hide it completely on just /docs