Fixed deprecation warning in Django 1.6.5 admin

Closes #95
Better handling of .select_for_update() and friends

Basically ._for_write no works same as write_only.
Fixed fake cacheops
Smarter get_queryset/get_query_set patch
Make it run in Django 1.7

Use AppConfig to initialize.
First stab at Django 1.7 support

Mostly a transition from tuple conds to lookups.
Removed erroneously left line
Fixed everything for Django 1.6-
Make benches work with Django 1.7
Run benches for Django 1.7
Added tests against Django master
Permit exact bench selection
Added pickle/unpickle benches
Updated benches

- removed old master/scripting ones
- add benches for current master with Django 1.6 and 1.7
Updated CHANGELOG to say Django 1.7 is supported
Separate testing for Django 1.7 and Django master branch
Revert to default Travis notification settings
Proper tests for M2M with explicit through model
Use app registry in Django 1.7 instead of INSTALLED_APPS introspection
Refactor installation using @once and @once_per() from funcy 1.1