Order by date and time

[Ed McDonagh]

Interface currently orders by date but not time in the day.

[Ed McDonagh]

http://django-filter.readthedocs.org/en/latest/usage.html#get-ordering-field

[Ed McDonagh]

Added override of get_filtering_field() to enable ordering on multiple fields, ie date then time. Implemented and tested for CT, implemented with limited testing for fluoro - only two exams in database on same date, implemented with no testing in mammo - no exams in test database. Fixes Issue #37. Also changed the order of the Total DLP to list the highest DLP first in CT.

→ <<cset a26c5b7e4d21>>

[Ed McDonagh]

Updated changes re issue #37.

→ <<cset ae13e0ff0705>>

[Ed McDonagh]

Removed note about study time ordering introduced in 0.3.8. Refs #37.

→ <<cset d3a9f42158a1>>