initial implementation of private collections

Former-commit-id: 4bcc8ad628fa48de5adb291197490117a3758f93
second round of private collections implementation

Former-commit-id: ed1c5c8383025a216a1b47edd9fceff7a68776c0
secured file downloads, added private url scheme for API

Former-commit-id: a27b2f8cc68f97f449168d4059a461b0e1098927
fixed unsecured data table api views

Former-commit-id: ffb17db102504b8ed0d8ae9e13185442edc80c6a
fixed api datatable access from views

Former-commit-id: 57932cd26b56e2820fdcb7d96d64f705feb45039
manually merge (repo filesystem issue: secured pycortex, more fixes to private collections

Former-commit-id: fcb001de3d6531fa950a9dac4c3de5304357a086
Merge pull request #1 from infocortex/enh/private_collections

Enh/private collections
added additional support for Nginx private media
added taggit south modules
Fixed serving of files in private collections
fixed a file matching bug
Changes add for neurosynth text to reflect private collections.
fixed file selection for serving view
API is not exposing private collections anymore
Remove users and groups from the API
Make licensing information more explicit.
add debug file streaming
comment out debug stuff
renaming
added template files