Celery Manager

[ryannova]

Create a celery manager that automatically manages the celery workers and restarts them accordingly when they have become unresponsive.

merlin manager command was added and there are 3 options run start and stop.

• run: starts the manager but is processing blocking but allows users to see the manager outputs and will be the main function for replacing merlin monitor for allocation management.
• start: starts the manager in a background process and is non-blocking.
• stop: stops the manager from a background or run process.