Merge pull request #18 from bradylarson/master

Changes to SectionAPI. Added setters to the model class and
Added polling APIs. Get a single section. Null check
in CourseAPI.

Added all the apis for polling functionality. Also added a way to
get a single section for a course. And there was a null check that
I added to a function in CourseAPI so it wouldn't crash if the course
array passed in was null.