make it ruby 1.9.x compatible

I already removed core_ext/proc.rb from master. If there is no more compatibility issue, consider it done.

Unit spec tests seem not to run so far. To simulate it, change any
green test in spec/unit. i.e. change
feed.title.should == "new title"
to
feed.title.should == "new title2"

With such a failing change, the build does not break in 1.9.2-head.
Therefore I guess its not running them (although its parsing those
files)

If any changes are made, use branch 84-ruby19