Moved duplicate code from CourseActivity and StreamActivity into base
class CascadeActivity.
Added static newInstance method to CourseBlogFragment.
Added static newInstance method to GradesFragment.
Added static newInstance method to SocialStreamFragment
Fragments in CourseFragmentAdapter are created using their static
newIstance(Course) methods to pass in Courses as args.
Added asynch loading framework to CourseBlogFragment.
Added async loading framework to SocialStreamFragment.