Rainbows! 0.95.0 - sendfile() support!

In addition to the 1.9-only IO.copy_stream, the new sendfile
1.0.0 gem may optionally be used with most concurrency models
(even under 1.8).

See http://rainbows.rubyforge.org/Static_Files.html for more info

Other changes:

* 1.9 encoding bugfix for (Rev)FiberSpawn and FiberPool
* fixed potential rack.input corruption with Revactor
* ThreadPool graceful shutdown no longer blocks until timeout
* optional ServerToken middleware for to display Server: header
* Dependencies bumped to Rack 1.1+ and Unicorn 1.1.0+
* numerous internal cleanups, small bugfixes and speedups
* more concise website oriented at users