test on python 3.2
add support for python 3 in tests, common, and git
all unit tests pass with python 3.2
use exec() instead of execfile() for python 3 support
tell travis to only install unittest2 for python 2
use script to install requirements for travis
test on python 3.0, 3.1, and 3.3
remove travis testing of python 3.0 and 3.1

travis-ci does not support these versions
update supported python versions
Merge branch 'feature/python3-support' into develop