fence_ibm_powervs: add private endpoint and token file support (#597)
- Enhance fence_ibm_powervs.py
New features:
- support PER-enabled Power Virtual Server workspaces with network access to private endpoints
- support security token to load from file
Fixes:
- support unknown states for virtual system instances
- new defaults for variables power_timeout = "120" power_wait = "15" stonith_status_sleep = "10"
- changed longdesc