minor search changes to support reuses

- only depend on leaflet-directive if include_spatial
- use injector to resolve leafletData dependency
- add ability to disable query sync
- fix potential transclusion error in _general_filters

Awesome work on this, BTW - with very little effort, I was able to pull this in to a new app. The app will be using it's own map to help change the extent so I didn't want to pull in the leaflet stuff but found the current 'disable' approach was kinda incomplete. This addresses that.