devilry_developer: Added a management command to run all the tests.

Required for Django 1.6. See #497.
devilry_settings: Removed the old test runner.

We use devilry_run_all_tests and the python2.7+ test discovery now.

See #497.
devilry_settings.testsuiterunner: Removed.

Not used anymore after Django 1.6 update. See #497.
devilry_usersearch: Do not instanciate EmptyQuerySet.

Required for Django 1.6. See #497.
Updated all "{% url ..." tags for Django 1.5 changes.

Used:

	$ git grep -P "{% url [^'\"]"

to find the templates needing update.

Required for #497.
devilry_developer.testhelpers.soupselect: Include nonbreaking space in

normalize_whitespace.
devilry_examiner...test_singledelivery: Use normalize_whitespace.

Required for #497.
devilry_qualifiesforexam: Updated tests for Django 1.6.

The tests run fine when executed one at a time, but not when executed
as a whole for some reason. #497.
core: Renamed tests for compatibility with Django 1.6.

See #497.
requirements.common: Added a commented out spec for Django 1.4.

Makes it easier to switch between django 1.4 and 1.6.
core...test_pointrange_to_grade: Updated for the quirk described in #563.
core...test_pointrange_to_grade: Fixed

You can't execute queries until the end of the 'atomic' block.

Caused by the django 1.6 update. See #497.
core...test_pointrange_to_grade: Cleanup and fixed duplicate method name.
.travis.yml: Updated to use devilry_run_all_tests.
devilry_examiner: Removed the unused rest API code and tests.
devilry_examiner...test_singlegroupoverview: Use normalize_whitespace.

Required by #497.
devilry_qualifiesforexam: Fixed preview view.
Import new style urls for compatibility with Django 1.4.
devilry_qualifiesforexam_approved: Updated for Django 1.6.

See #497.
devilry_qualifiesforexam_points: Load url from future for Django 1.4

compatibility.