Move tests into a module.

Preparing to have more tests and better separate them out
Test areas_by_point with the current MAPIT_AREA_SRID

Always testing against SRID=4326 breaks when AREA_SRID or MAPIT_AREA_SRID are set to antything else, like 27700. We can't override_settings either because the settings are used in the migrations that create the database, so when testing they're accessed too early for us to nobble them.
Git-ignore .DS_Store files
Replace print calls with self.stdout.write

This will make testing the command easier and quieter
Raise CommandError for errors with options or input.
Move test setup into setUp not setUpClass

Django won't automatically rollback the things we create
in the database in setUpClass, so they leak into other tests
Add a basic test for importing KML files
Add smoke test for django admin pages
Add tests for JSONPResponseMiddleware