Travis integration tests

[gaul]

I could not run 3 of the 4 Paleo commands with the provided test inputs as reported in #3 #4 #5. Could you add integration tests to your .travis.yml so that I could be sure whether my environment creates these issues?

[gaul]

@etrain suggested that upgraded dependencies could cause this issue. In this case, Paleo could configure virtualenv to pin the necessary versions in requirements.txt.