This adds a "-T" flag to the harvest command which makes it operate on the Django test database(s). This can already be achieved using the "runserver" hooks in terrain, but I think this is cleaner.
I'm not sure if this is still wanted, since I saw another pull request by skoczen that fixes #73. It seems the concern there was that the behavior was made default and included another change that switched the live server.
Optionally use test databases for django server with -T command option