add python 3 to tests
exclude django 1.2 - 1.4 on python 3 since those versions of django don't support py3k
fix python 3k imports and add python 2.5, and 3.2 to travis
require at least django 1.2 and support wheel distributions
never mind python 2.5 - it's old and I don't have time for this
Merge branch 'refs/heads/master' into travis
Merge branch 'refs/heads/travis'
add travis build status to readme