Replace rcov with simplecov

Rcov does not work on Ruby 1.9.x as reported on their github page.
Add code coverage filter to include spec files
Ignore coverage folder
Ignore .DS_Store
Define helper to load online fixtures, update paths accordingly
Define helper to load shared fixtures, update paths accordingly
Define helper to load windows fixtures, update paths accordingly
Autoload spec_helper

Rspec2 auto loads the spec_helper.

http://stackoverflow.com/questions/5061179/how-to-load-a-spec-helper-rb-automatically-in-rspec-2
Simplified requires
Merge pull request #28 from whereisciao/refactor-spec-tests

Refactor Spec Tests