Rainbows! 0.90.1

This release contains minor bugfixes/compatibility improvements
for ThreadSpawn, ThreadPool and EventMachine users.

Excessive error messages from spurious wakeups using
ThreadSpawn/ThreadPool under most platforms are silenced.  Only
Ruby 1.9 users under Linux were unaffected by this bug.

EventMachine users may now use EM::Deferrable objects in
responses, vastly improving compatibility with existing
async_sinatra apps.