first revision of afni4d support
refactored afni slice save into containing formset- fixed bugs with edit&save
added upload folder support for afni4d
allow brackets in nifti name urls
added image validation script (wip)
added conversion script
refactored for DRYness and fixed tag copying
Initial implementation of collection sharing with Contributors
-Added Chosen for autocomplete multi-select of users for Contributors (skins a normal multiple select):
https://github.com/harvesthq/chosen
This should scale easily up to 1000s of users.
-Implemented form access/edit and delete permissions for Owners/Contributors
-Owners only have control over private/public of Collection also.

TODO:
-testing
-email notifications?
-listing of who is in group to other collaborators
- fixed ownership of contributors in add form
- moved util functions to util
- fixed folder name bug in upload_folder (also fixed in enh/afni4d)
fixed my collection for contributor
added templated email notifications
added the actual things...
serialized contributor names for api
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