Added gemspec, fixed Rake tasks and test suite so that it runs in Ruby 1.9

This is my fix for #46.  I think it's a bit cleaner than what @alexhanh has in his copy of the project because the `rake test` works (and actually runs the test suite) in my copy of the project.

Pulling this in will allow others to actually use a copy of the gem directly from this repository, as well as any forks of this gem.