test basic node HTML responses using HTMLUnit

Fixes https://www.pivotaltracker.com/story/show/60188408
expose java errors from select ajax requests
add HTML rendering for fcr:nodetypes
fix up namespace form to use bootstrap form groups
Update FedoraContent to do the right thing with the Slug: header, and remove fcr:new reference.
Fix backup and versions tests to mint unique object ids
Merge pull request #140 from futures/htmlunit

test basic node HTML responses using HTMLUnit