updated podspec for new version
manual merge
Merge remote-tracking branch 'upstream/master'
Added an enum for submission types and fixed the update URL.

Also changed assignment API to return needs_grading_count_by_section
Merge pull request #162 from bpluim/submission_fix

Added an enum for submission types and fixed the update URL.
updated podspec for new version
Adding previewURL to CKIFile
Merge pull request #163 from bpluim/previewURL

Adding previewURL to CKIFile
updated podspec for new version
Merge remote-tracking branch 'upstream/master'
Corrected the submisison path and added the context transformer so it will transform Assignments
Merge pull request #164 from bpluim/submissionPath

Corrected the submisison path and added the context transformer so it wi...
updated podspec for new version
Preventing crash when there are no assessments and changing score to NSNumber
Merge pull request #165 from bpluim/score_nsnumber

Preventing crash when there are no assessments and changing score to NSN...
updated podspec for new version
Merge remote-tracking branch 'upstream/master'
Adding discussion topic id to an assignment.
Merge pull request #166 from benkraus/master

Adding discussion topic id to an assignment.
updated podspec for new version