Merge pull request #67 from hhoang/master

Added setter for a submission's rubric_assessments
Merge pull request #68 from hhoang/master

Support for needs_grading_count_by_section
Merge pull request #69 from hhoang/master

Added canvadocs preview_url for attachments
Merge pull request #70 from hhoang/master

Added published attribute to Assignment object
Group Category support for canvasAPI

Enables user to get a list of users that belong to a group_category id