Ticket #161

- Created API function to check whether enough answers exists
for the user to do a minimum of one comparison
- This is based on the number of eligible answers and dividing it
by 2. If the result is 1 or more, than the function returns True
- Ineligible answers include:
	- instructors
	- TAs
	- dropped students
	- current user
	- authors of evaluated answers by current user
- Tests need to be written for the two new functions.