Added CourseInstanceSummaryResource to api
/course_results/ returns the same as /courseinstace/, course_results/course_id/user/user_id/ returns what users summary for the course instance, rest are left as TODOs
CourseInstanceSummaryResource now moved to course/api.py. /api/v1//course_result/course_id now returns empy list. resource_name changed from 'course_results' to 'course_result'
Code formatting fixed
Merge pull request #87 from LassiHaaranen/master

CourseInstanceSummaryResource added to API. Closes #87. Closes #90.