Process execution metrics

Object name: com.clcbio.server:type=ProcessExecution

Process execution metrics allow measurement of how many jobs are being processed and how many are in a queue because they are waiting for available processing resources.

On job node setups, the object names are available on all nodes, but it only makes sence to monitor them on the master node since this is where the jobs are managed. If a grid is used to process the jobs, the actual queue will be a part of the grid system, which results in the processes being moved almost instantly to the "currently processing" state and the CLC Server queue itself is then empty.