Add three new SLURM API calls:

  - slurm_allocation_lookup (replacement for slurm_confirm_allocation)
  - slurm_signal_job
  - slurm_signal_job_step

slurm_allocation_lookup uses the same back-end RPC as
slurm_confirm_allocation, but that RPC no longer looks at the "uid"
entry in the structure.  slurm_confirm_allocation is marked OBSOLETE.

scancel uses slurm_signal_job and slurm_signal_job_step any time the "-s"
option is used to directly talk to the slurmds and signal job steps.
Only when there is no "-s" does scancel ask the controller to do the
signalling with the slurm_kill_* functions.

Set the svn:keywords property that was missing on some slurmd files.