Release 0.15 of django-filter breaks OpenREM

[Ed McDonagh]

AssertionError at /openrem/ct/
get_order_by() has been deprecated. Subclass OrderingFilter and override .filter() instead. See: https://django-filter.readthedocs.io/en/latest/migration.html"
Request Method: GET
Request URL:    http://192.168.56.102:8000/openrem/ct/?display_name=Royal%20Marsden%20Hospital%20rt16&o=-study_date
Django Version: 1.8.14
Exception Type: AssertionError
Exception Value:    
get_order_by() has been deprecated. Subclass OrderingFilter and override .filter() instead. See: https://django-filter.readthedocs.io/en/latest/migration.html"
Exception Location: /home/rem/virtenv/local/lib/python2.7/site-packages/django_filters/filterset.py in __new__, line 200

[Ed McDonagh]

Looked at using the new OrderingFilter, but it is not obvious how to implement it, including overloading it to add time ordering into the date ordering. Locked to <0.15 instead. Refs #436

→ <<cset b329f586680d>>

[Ed McDonagh]

Pegged django-filter at 0.14. Fixes #436 for now.

→ <<cset 71b1f28180df>>

[Ed McDonagh]

Fixing ref #436 for release 0.7.4b1

→ <<cset b065aa30d613>>

[Ed McDonagh]

See ref #437 for issue tracking proper fix.