Show statistics about number of users checked into tags by application branch

[evan10s]

A common statistic we need to know is how many of a given type of applicant showed up to an event. For instance, if the application branch types were Participant, Mentor, and Staff, then the output would be:

branch	hackgt	workshop1	meal1
Participant	400	100	250
Mentor	50	3	45
Staff	50	3	45
Total	500	106	340