Ruby 2.0.0 ifying

Jeweler 1.8.4 has lots of trouble working in the newly released ruby2.0. The biggest problems is that 2.0's rubygems uses Gem::Package instead of Gem::Builder, so I changed that in build_gem (in lib as well as in test) to reflect this change. In addition, ruby2.0 must use the newest bundler 1.3.0.pre for function correctly.

In addition, as there is currently no working debugger for ruby2.0 yet, I removed the debugger from the gemfile. Finally, I should mention I had to do some shenenigans with simplecov and rcov with conditionals in the gemfile to be able to properly use the rake and whatnot features of jeweler.