Gargoyle

- Added basic switch inheritance.
- Added auto collapsing of switch details in interface.
- Added simple search filtering of switches in interface.

- Improved display of Gargoyle dashboard widget.

- Fixed switch_condition_removed signal to pass ``switch`` instance.

- Updated signals to pass more useful information in each one (including the switch).

- The percent field is now available on all ModelConditionSet's by default.
- Fixed a CSRF conflict issue with Nexus.

- Added gargoyle.testutils.with_switches decorator
- Added gargoyle.testutils.SwitchContextManager