[testing] Integrate with Travis CI
[testing] Integrate with Travis CI

Add the Travis CI build configuration so that the repository can be
tested using continuous integration.

silgon/pymdptoolbox,sawcordwell/pymdptoolbox,yasserglez/pymdptoolbox,sawcordwell/pymdptoolbox,yasserglez/pymdptoolbox,McCabeJM/pymdptoolbox,silgon/pymdptoolbox,McCabeJM/pymdptoolbox