Merge pull request django-haystack#1596 from klass-ivan/collecting-de…

…ep-attr-through-m2m

Fixed collection of deep attributes through m2m relation

Optimize ElasticSearch backend (closes django-haystack#1590)

Thanks to @klass-ivan for the patch

Use Python 3-compatible version comparison

Changed GeoDjango Link

Changed GeoDjango link from geodjango.org to https://docs.djangoproject.com/en/1.11/ref/contrib/gis/

PEP-8

Update changelog

docs: work around ReST pedantry !cosmetic

Bump version to 2.5.dev2