Add needs_grading_count flag when fetching assignments

There's already a property for this on the model, but it
will never have a value because we don't fetch it.
add needsGradingCount to CKICourse

the property was there, but the mapping wasn't hooked
up so you were never getting any values
Merge remote-tracking branch 'instructure/CanvasKit/master'
refactor CKIAssignment
fixing up rubrics
add to umbrella header, clean up
make assignment groups return assignments
actually use params from last commit
Changes to Admin forced Canvas login
minor adjustments to models

rename a few properties, adjust types, etc.
fix for enrollment crash when fetching course by id
Merge pull request #111 from instructure/jsonapi-support

fix for enrollment crash when fetching course by id
Only bail on 401s after attempting to fetch current user

if another 401 occurs when fetching the current user, then we know we
have a problem and should bail.
Merge pull request #112 from derrh/jsonapi-support

Only bail on 401s after attempting to fetch current user
Merge pull request #113 from instructure/jsonapi-support

Adding an additional check on 401 errors before forcing a logout.
added property to the poll session
Merge pull request #114 from instructure/jsonapi-support

added property to the poll session
added some poll submission properties and poll session properties
Merge pull request #115 from instructure/jsonapi-support

added some poll submission properties and poll session properties
added jsonapi support for updating model objects