Port the `from_python` method from pyelasticsearch to the Elasticsearch backend, similar to `to_python` in 181bbc2c010a135b536e4d1f7a1c5ae4c63e33db.
Port the `from_python` method from pyelasticsearch to the Elasticsearch backend, similar to `to_python` in 181bbc2c010a135b536e4d1f7a1c5ae4c63e33db.

Fixes #762. Refs #759.

mixcloud/django-haystack,Stupeflix/django-haystack,streeter/django-haystack,fisle/django-haystack,dionysio/django-haystack,vitalyvolkov/django-haystack,antonyr/django-haystack,sgaist/django-haystack,celerityweb/django-haystack,antonyr/django-haystack,streeter/django-haystack,fisle/django-haystack,celerityweb/django-haystack,cyanut/django-haystack,kybi/django-haystack,ruimashita/django-haystack,django-searchstack/django-searchstack,jannon/django-haystack,askaliuk/django-haystack,barseghyanartur/django-haystack,elishowk/django-haystack,jannon/django-haystack,sgaist/django-haystack,Architizer/django-haystack,eventials/django-haystack,elishowk/django-haystack,django-searchstack/django-searchstack,fisle/django-haystack,comandrei/django-haystack,eventials/django-haystack,celerityweb/django-haystack,comandrei/django-haystack,barseghyanartur/django-haystack,zeehio/django-haystack,Architizer/django-haystack,blancltd/django-haystack,streeter/django-haystack,ruimashita/django-haystack,speedplane/django-haystack,blancltd/django-haystack,kuanyui/django-haystack,cyanut/django-haystack,cyanut/django-haystack,antonyr/django-haystack,barseghyanartur/django-haystack,mixcloud/django-haystack,speedplane/django-haystack,dionysio/django-haystack,vitalyvolkov/django-haystack,zeehio/django-haystack,askaliuk/django-haystack,comandrei/django-haystack,django-searchstack/django-searchstack,kuanyui/django-haystack,ruimashita/django-haystack,askaliuk/django-haystack,speedplane/django-haystack,jannon/django-haystack,kuanyui/django-haystack,eventials/django-haystack,Stupeflix/django-haystack,kybi/django-haystack,vitalyvolkov/django-haystack,Stupeflix/django-haystack,zeehio/django-haystack,elishowk/django-haystack,blancltd/django-haystack,sgaist/django-haystack,dionysio/django-haystack