unicorn 2.0.0pre1 - a boring "major" release

Mostly internal cleanups for future versions of Rainbows! and
people trying out Rubinius.  There are tiny performance
improvements for Ruby 1.9.2 users which may only be noticeable
with Rainbows!.

There is a new dependency on the "kgio" library for kinder,
gentler I/O :)  Please report any bugs and portability issues
with kgio to the Unicorn mailing list[1].

Unicorn 1.1.x users are NOT required nor even encouraged to
upgrade yet.  Unicorn 1.1.x will be maintained for the
forseeable future.

[1] - mongrel-unicorn@rubyforge.org