Document encoding of docId URL parameters.

The docId URL parameter cannot include slashes, so Zanata expects
every '/' to be replaced with ','.
Fix invalid end point projects/p/tiny-project/iterations/i/1/r/hello
Add endpoint for translation states.

Adds an endpoint under the document for fetching translation state
of each string in the document into the given language.
Merge branch 'master' into pull-request