Renamed/refactored some properties and names on SISCourseData object.  Created a mixin to define the "contract" for object that gets returned by data access layer.  Add tests for the mixin.
Merge pull request #14 from Harvard-University-iCommons/feature/course_data_model_update_with_tests

Renamed/refactored some properties and names on SISCourseData object.  C...