Process list should use various verbs describing state

The process list page should use various verbs to better represent the current state of the workflow. Currently, even if a process is unscheduled, it shows "running for X Minutes" in the Duration column.

I suggest the following, where X is the duration:

• "Pending for X" for pending & unscheduled states
• "Running for X" for running state
  • this is already OK
• "X" for final states: stop states, error states & completed
  • this is already OK