ST2 and ST3 Compatible

This new branch places the original plugin and my new ST3 version into separate packages, named **python2** and **python3** (maybe better names would be appropriate?). The new master `rake.py` just imports the correct version based on the current python version in use.  There might be a way to truly combine the two versions into one master file, but I really think this is cleaner because it allows each version to be developed independently and in the best way for each Sublime API.