zproc pernight and cumulative jobs can't run without exposure tables

[akremin]

The original intention of zproc inputs expids and nights was to allow the user to explicitly specify the expids and nights they wanted to go into a pernight or cumulative redshift job. This is no longer true due to the "else" statement on line 349. There the exposure_tables are read in and only the expids that are found in the exposure tables are kept.

This should be updated such that if all data (nights, tileid, expids, camword) are specified, then the job can proceed with trying to perform the redshift fitting.