Add several metrics

[GalaxyGorilla]

• Scheduler usage, e.g. per scheduler a number between 0 and 1 will be generated which shows the exhaustion of each scheduler

  Further infos from the recon docu:

  "For any time interval, Scheduler wall time can be used as a measure of how 'busy' a scheduler is. A scheduler is busy when:

  • executing process code
  • executing driver code
  • executing NIF code
  • executing BIFs
  • garbage collecting
  • doing memory management

  A scheduler isn't busy when doing anything else."

• Start time of the metricman application to get an approximate value for the start time of the BEAM.
• Uptime of metricman to get an approximate value for the uptime of the BEAM.

Every time measurement is in ms.