Implement Rex interface for managing iLO ME

[amaxine]

Fundamental support in #17.

This could use expanding to correctly parse iLO output:

</>hpiLO-> show

status=0
status_tag=COMMAND COMPLETED
Mon Jul 15 09:16:20 2019



/
  Targets
    system1
    map1
  Properties
  Verbs
    cd version exit show