Django-simple-elasticsearch

---------------------

* Added in new `post_indices_create` and `post_indices_rebuild` signals to allow users to run actions at various points during the index creation and bulk indexing processes.

---------------------

* fixed an issue where per-item request parameters were being added to the bulk data request JSON incorrectly. Tests updated.

---------------------

* added warning if Django's DEBUG=True (causes out of memory errors on constrained
systems due to Django query caching)
* added index setting modification on rebuilding indices to remove replicas, lucene
segment merging and disabling the refresh interval - restoring the original
settings afterwards.

---------------------

* added `page` and `page_size` validation in `add_search()`

---------------------

* Renamed search form related classes - more breaking changes. Added in support
for Django's pagination classes (internal hack).

---------------------

* Revamped search form related classes - includes breaking changes.