Merge pull request #10 from ambitioninc/master

Merge pull request #9 from ambitioninc/release
removed super entity activity relationships.
Merge pull request #12 from wesleykendall/develop

Removed is_active filtering on relationships
converted django entity to use model manager utils
pep8
updated the requirements for proper instatllation
updated tests to verify that package can be installed
updated documentation for cached_objects model manager
created an assertion for the number of queries that get executed
created a new way of filtering sub and super entity relationships
added get_for_obj function and changed all tests to use it
documentation changed for the new filtering methods
added ability to intersect super entities of the Entity manager
pep8
tested intersection of super entities and verified it only results in one query
updated requirements since setup is ran before install
setup postgres db creation for travis
provided the ability to intersect with no super entities
tested is_type and is_not_type filters
added one more test for intersection with type filtering