Python 3 compatibility and pep8 error fixes

[iambibhas]

While trying to install this package to use with our Py3 project, saw that it was breaking because it wasn't using the relative import. So added that. Also added a simple test case. And also testing with Travis that it works with Python 2.6 to 3.4 - Also, fixed a lot of pep8 errors, except the 80 char limit and unused import ones.