incorporate @certik suggestions
Merge pull request #215 from hashdist/ahmadia/refactor_python_packages

Refactor Python packages
Update matplotlib to version 1.3.1.

I added a licence field as discussed in
https://groups.google.com/forum/#!topic/hashdist/aJQkqm9hZZw
Sort travis test cases alphabetically.
Separate out testcase for matplotlib.