Investigate MANIFEST file

[jorgepiloto]

In #3 I disabled MANIFEST checker in tox when running the tests. This file is supposed to hold the paths and files that are included in the sdist when sharing the package. More information can be find in:

https://docs.python.org/2/distutils/sourcedist.html

However I was not able to make manifest to check and include the different directories. I would like to solve this issue before the first release of the package.

[jorgepiloto]

In #6 I also disabled MANIFEST checker in Travis, just to remember that when coming back to this in future 🚀