Need to require ack-and-a-half for it to work

I guess I didn't test this as well as I should have previously. It would
appear that defvar without a value still leaves it as void. Since the
function references the arguments before autoload brings in
ack-and-half, it's used in projectile while still void.
Merge pull request #276 from dgtized/fix-ack-for-real

Need to require ack-and-a-half for it to work