Merge tag '1flow-0.27.4.5' into develop

0.27.4.5 1flow-0.27.4.5
Move sparks dep. In the meantime, Update sparks requirements to use @develop branch to test with Dj1.6, then get back to @master when everything is OK.
Requirements refresh #1: basically, all github repos switch to master, and JSONfield is back to the original author's repo.
Django-user-accounts switches to a github repo because PYPI version doesn't work with Django 1.6.
Refresh dev-reqs for Django 1.6, notably devserver @tag because patch is not yet on PYPI.
Don't fail importing deprecating things, particularly if they are useless too.
Stop using redis-sessions, and switch to using django-redis only for cache and sessions. 

This drops one more memcached dependancy (still, at least select2 uses it).
Use django-constance @master for Django 1.6 compatibility.
PEP8 happyness.
Remove obsolete GRI admin models, Django 1.6/mongoadmin cleanups.
Re-activate redisboard in the admin, remove memcache-status (not relevant as only small external projects are stored in memcache now).
Remove obsolete settings.
Remove our now-obsolete admin.autodiscover, to use Django's.
Add a shame-on-developers filter.
Re-order and refresh constance config, for the upcoming block-based admin interface.
Re-order again the constance settings, to match the upcoming order they are displayed in.
Make the constance config better looking and organized.
Remove all references to django-cache-utils, we don't use it anyway.
Enhance Constance+Grappelli styles.
Add @elitberriot settings.