Add `tox` and `coverage` for testing.

`tox` create clean environment for testing and it can specify Python and
django version.
Add installing/testing/running documentations
Fix README issue
Add MANIFEST file
Update README
Add .coveralls.yml for command line usage
Specify python version to run correctly coveralls
Merge pull request #24 from kawazrepos/add_new_testing_storategy

Add new testing storategy