Fix for issue 29

Changed “unittest” directory to “testing” to avoid namespace collisions
with the Python unittest library.
Merge branch '20140301_fix_unittest_namespace'
Moved calculate_dvp_rank from the utilities directory to root.
Modified calculate_defense_vs_position to make sure value is not None

This could be the case for a situation like the first game of the
season.  Without this check, we get database errors.