Rainbows! 4.5.0 - hijacking support

This release adds hijacking support for Rack 1.5.x users.
See Rack documentation for more information about hijacking.
Lin Jen-Shin also provided the -N/--no-default-middleware option.
Minor packaging cleanups and new HACKING document.

There are also some corner-case bugfixes for *Epoll* users
(sleepy_penguin, these bugs do not affect EM or Cool.io users)
and test suite portability improvements.