Post-session evaluations

Here's Ezra's work from #930072: Post-session evaluations base functionality with a hook_node_validate() to prevent multiple evals of the same session by the same person and fivestar fields matching London's.

Remaining work:

• token doesn't work for node title, "coltrane's evaluation of [node:field_eval_session]"
• Get the "Evaluate this session" link in place
• Test

The fields split off as a feature

I've deployed this on http://test-denver2012.redesign.devdrupal.org/

Still experiencing token fail on auto nodetitle.

Need to theme the "Evaluate this session" link too.

Token title working now. Was probably that we were on beta3.

Updated feature has been committed with style changes.