Revert "Revert "Remove dual-type support for Languages and Categories""

The Parsoid team says the cache is clean of old language /
category types, and would like us to use the new types
for newly generates languages/categories.

This reverts commit d8dcafe25bf3c0ce1fb07b43bf3e8c97e1ba574d.

Change-Id: I0cffd5d299624230f3805f9468b2497f392c12c0
Merge "Revert "Revert "Remove dual-type support for Languages and Categories"""