Added AssignmentID's to Submissions
Section extends CanvasContext

Currently our CanvasRestAdapter namespaces API calls to 'api/v1/courses', 'api/v1/users' or 'api/v1/groups'.
This commit adds support for API calls to  'api/v1/sections'
Merge remote-tracking branch 'upstream/master'
Added students list to sections API and fixed parcel methods for submissions
Merge pull request #24 from hhoang/master

Sections extend CanvasContext and Added AssignmentID's to Submissions