Extend SimulationWorkload with CPU flags

Extend SimulationWorkload with CPU flags

Added flags for PME and Nonbondeds to indicate whether there is CPU
workload; this is useful as the lack of GPU work does not imply the
existence of CPU work.

Also made createSimulationWorkload() take the PME runmode class enum
instead of a bunch of bools.

Made some naming consistency improvements.

Refs #3181

Change-Id: I66233f1c790fc5092fb1babaed2ec3ebf16416de