(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
Line of code here is repeated twice. Maybe it would be best to make a function that generates the password, and a wrapper function that simply calls the generation function:
```python
password = generate_new_password()
while password in generate_passwords:
    password = generate_new_password()
```

That way if you want to change how passwords are generated you don't have to change the logic in 2 places.