Analyst dashboard2

Rewrote analyst dashboard, moved much of completion table to utils.py, added Bayo's template tags (though had to reproduce feedback_rate_table function in clinics.views for ajax recalcs) and added unit tests.
I think canonical is::

get_completion_query(responses=None, clinic=None, service=None, start_date=None, end_date=None):

or::

get_completion_query(*args, **kwargs)