Convert doctests to nosetests and configure Travis to run them.
Renames pandaspark to sparklingpandas.
Merge pull request #17 from jhlch/change-name

Renames pandaspark to sparklingpandas.
Conform to PEP8
Merge pull request #18 from jhlch/pep8

Pep8
Initial groupby support
Cleanup
Add back the missing import of pandas for the dataframes
cleanup a bit more
Add groupby and groupby tests back
Use run-tests
Update text in run-tests if SPARK_HOME is not set