LP#1198465 Stop using storage wrapper for generate_fines()

LP#1198465 Stop using storage wrapper for generate_fines()

With pieces now in place, let's stop using the storage wrapper for
generate_fines() and call the code directly.

Also, to avoid potential confusion, rename the calling function in
Circulate.pm from generate_fines() to handle_fines().  This function
may also be taking on more than just fine generation in the near future.

Finally, since the new generate_fines() expects one or more pre-filtered
circ objects, add the requisite stop_fines check to handle_fines().

Signed-off-by: Dan Wells <dbw2@calvin.edu>