YACS should fetch months in the next year

[jeffh]

It seems like this code: https://github.com/jeffh/YACS/blob/c7921b171ee5127f5c1b0e166213aa7ea0eea418/courses/bridge/rpi.py#L309-L316

Doesn't properly fetch if the semester wraps to the next year:

(Using semester 2015-09 should produce the url of next year).

This prevents YACS from automatically see the new semester.

[jeffh]

Update: YACS server seems to hang when it attempts to repeat import of the current semester information...