Merge pull request #156 from derrh/master

Viewing submissions for students
Merge pull request #157 from derrh/master

updated podspec for new version
Minor changes to files and submissions.
Merge pull request #158 from bpluim/SubmissionComments

Minor changes to files and submissions.
updated podspec for new version
Added public property of rubricCriterion, and added mediaComment to ckisubmission when submission is a media comment.

Also added position data to CKIRubricCriterion for proper ordering.
Updated Podspec
Merge pull request #159 from bpluim/MediaCommentSubmissions

Media comment submissions