added query by DOI option, closes #35
list all images for every collection, closes #39
fixed permissions
Merge branch 'enh/api_old'

Conflicts:
	neurovault/urls.py
Added StatisticMap.
migration cleanup, add polimorphism
Conflicts:
	requirements.txt
make polymorphism play with rest API
Conflicts:
	neurovault/urls.py
add missing ContentType when adding polymorphism
Fixed polymorphism related bug in the REST api
Conflicts:
	neurovault/urls.py
formsets do not work with polymorphic - switching to addign images one
by one
remove NIDM Results leftovers
added atlas file format
Added Atlas class
removed editimages artefact
added REST API serialisation for Atlas
zip and folder uploads are not atlas aware
Added NIDMResults class
make custom templates for each class
List types of maps in collection view.
Image forms refactor