Algoliasearch

* [FIX] Default to model.pk instead of 'id'

* [FIX] Fix --batch-size of reindex command on Django 1.7

* [FIX] Check that geo_field callable returns something valid

* [FIX] Compatibility warning with Django 1.9

* [ADD] `get_queryset` for grain indexing possibility
* [ADD] Option to deactivate auto-indexing
* [FIX] Various bugs

* [REMOVE] algolia_buildindex command. Use algolia_reindex instead.
* [CHANGE] Settings format. Last format is still supported.
* [ADD] Unit test.
* [ADD] Tag capacity
* [ADD] Conditional indexing
* [ADD] Search capacity on backend
* [FIX] Invalid custom_objectID attribute
* [FIX] Exception throw by the command when using Django 1.7