Replace wordpress-unit-tests with new wordpress-develop/tests

* Removes the massive checkout of wordpress-unit-tests
* Uses the new tests directory in the develop.svn repo to handle unit testing
* Because I haven't dug to see if we can initiate tests differently with wp-cli, we are copying over a prefab config file. This may change down the road as wp-cli adapts (or I read documentation)

Work toward #113