Adding body parameter to swagger models if it's a class
Preserves the order of fields as declared in serializers
Pass fields help_text to swagger as field description.

Conflicts:
	rest_framework_swagger/docgenerator.py
Pass fields help_text to swagger as field description.
fix help_text handling for new data format
fix choice/enum handling for newer rest framework
Merge remote-tracking branch 'gregbaker/develop' into develop-new
Merge remote-tracking branch 'jakob-o/refactoring/preserve-field-ordering' into develop-new
Merge remote-tracking branch 'jakob-o/feature/discover-body-models' into develop-new