Cleanup

* Fixed syntax errors.
* Got tests passing on 1.8.x and 1.9.x.
* Moved classes into separate files.
* Created classes for each Service.
* Moved URL extracting logic into `#on_response` and `#on_body` methods.
* Updated the gemspec to use `git ls-files`.
* Use `RDoc::Task`.
* Removed `doc/` from git.