WL-98 As a course instructor, auto-register (as well as auto enroll) a list of students into my course

@chrisndodge here are the changes related to WL-98 for your quick reivew. 
we have written the test cases but only one coverage is missing in our code.  
currently we did not check/test the code for quality.

In order to test this feature you need to set the flag: 
FEATURES['ALLOW_AUTOMATED_SIGNEDUPS'] = True
Read through this--
https://docs.djangoproject.com/en/1.4/topics/http/file-uploads/

No example of closing the file handler from request.FILES, so I guess it isn't an issue (feels wrong, especially coming from Java where it is hammered into you that you MUST always close a file, and in a try/finally cause).

If there is a possibility that the uploaded file is "huge", it is better to read the file with "chunks". I doubt that is an issue in this PR.