fix Travis CI builds install httpretty explicitly in travis.yml and use py.test instead of setup.py test
fix Travis CI builds
install httpretty explicitly in travis.yml and use py.test instead of setup.py test

cameronbracken/ulmo,ocefpaf/ulmo,ocefpaf/ulmo,nathanhilbert/ulmo,nathanhilbert/ulmo,cameronbracken/ulmo