Added term query to search page


![query_by_term](https://cloud.githubusercontent.com/assets/2644780/3714550/6ad8b9b2-15af-11e4-87df-362ddd3cdd26.png)
Fixes #65
This is not in general a robust way of getting the next term. You are assuming here that `current_term_num` and `next_term_num` will always be a single digit, which is true for now, but it is not good to rely on this assumption. It is very easy for someone to go and change the term numbers in `util.py` and completely miss this implicit assumption here. Please do this is in a more robust way. Also, I'm not sure you want to do it like this at all given the comment below. You'll want the year as well... `2014_09`, not just `09`. If we're going to be honest about "this term" and "next term", next term means "2014_09", not any "09". And it is generally not true that a course offered in the fall term gets offered every fall term.