Updating rest to allow raw form values.

Form values take a few different forms in the gerrit api, so let's make
it easy on ourselves and allow them to be passed in raw by the clients
when needed.

Change-Id: Ic6db7ccb03f451b4c54bfd69ca6095df51deebc5
Merge branch 'go' of https://github.com/guildencrantz/grt into go