Scheduling controls on queues and labels

[MustafaI]

Summary of changes:

• Ability to pause/resume scheduling per-queue
  • Queued demand for paused queues not considered in fair share calculations
• Ability to label queues
• Armadactl scheduling controls based on the above features:
  • Added control-scheduling command with pause and resume sub-commands
  • match-labels, match-queues, dry-run and inverse flags on sub-commands allow better transparency and control on actions being taken.