Adds "All Data" filter to case list report

Addresses this ticket:
http://manage.dimagi.com/default.asp?121778#688842
It adds an "All Data" filter by modifying the `CaseListMixin` class that is subclassed by `CaseListReport`. I've examined the code of `CaseListReport`'s descendants, and none of them seem to cause conflicts with the changes made.
The latter is a slight variation of the original view, controlled by that optional kwarg.  You could also make it one line like so:

    url(r'^emwf_options/(?:/(?P<all_data>all-data)/)?/$',
        api.EmwfOptionsView.as_view(),
        name='emwf_options_with_all_data'),
I think two separate lines is clearer though.  I guess you could just have the second url point to a subclass of the view.
@biyeun thoughts?