Feature/rails3

I wanted to use the rsemantic gem in a Rails app. Rails couldn't find the Semantic module as it assumes that it follows convention and was looking for an Rsemantic module. I've renamed the module Semantic to RSemantic so the gem can be used with Rails. All specs pass.

In addition I've replaced all deprecated RSpec functions with their modern replacemants.

Finally I've added Guard-RSpec for continues testing, but this is more a personal preference.