(WIP) 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
Well, I wrote up that specification, my sense is that the email will be the known element in the use-case. For example, I am working at BigCorp and I want to sent a list of 100 of my employees to take a course. I know their email address at my company, but I don't know if they happen to have an edx account (which might use this BigCorp.com email address). 

Make sense?