avoid rspec 2.x deprecation complains
rubyforge no longer exists - just point to github repo + do not mention Merb :)
support filtering jars to be mvoed to WEB-INF/lib with `config.move_jars_to_webinf_lib`
improve the `config.move_jars_to_webinf_lib` filter to match the default added jars

allows for quite "strangely" looking but very valid use-cases such as moving the jruby core jars upper in the class-path hierarchy (e.g. for faster re-deploys and less leakage) or if someone uses a custom - patched jruby-rack jar due a bug or a use-case of their own.

it's not expected to be used by default, yet if the filtering is there it might as well be applied to all jars we move by default to WEB-INF/lib
updated default warble.rb to include new details about move_jars_to_webinf_lib