EDX-651: Fix TypeError when sorting oa_items
Merge pull request #34 from yokose-ks/EDX-651

EDX-651: Fix TypeError when sorting oa_items
EDX-634: Fix max size of upload file for submission
EDX-638: Disable submit button before file is uploaded
EDX-637: Upload an image file using boto
EDX-639: Fix UI for file upload (remove file__upload button)
EDX-641: Verify uploaded file type more strictly
EDX-644: Check for File API & HTML5 support
EDX-643: Add unit tests for file upload
Add translation files