Be more patient with IPMI and BMC

Before the ipmitool driver called 'power status; power on' in a loop
which made the IPMI/BMCs not behave well.  Also the total time we would
wait (5 seconds) wasn't always enough.  So make sure power on/off is
only called once and wait up to 10 seconds for the power state change to
go into effect.

This is a port of change-id I5a4d7c84ebdf9c1f7d8d0570dbc31764c31f1fc6

Change-Id: I50982b24e5443b34d5597581ea2947a0301d35c9
Closes-Bug: #1234479
Merge "Be more patient with IPMI and BMC"