Deadline scheduling updates

Move some un/pack logic for deadlines, They were placed in the wrong
  location due to confusion by the "patch" command
Moved variable definitions to the top of a block
Break up some long lines into multiple lines
Do not change a job's time limit to satisfy deadline, treat it like
  an error (unless the time_min is set, in which case the time limit
  can be lowered to that level)
Remove logic checking for job_specs->deadline == NO_VAL, that is never set
Fix logic in backfill scheduler that was treating a job's time_min
  as a valid value and changing the job's time limit to that value
  rather than indicating no value was set