Add console interface to agent_ipmitool driver

The agent_ipmitool driver (ironic.drivers.agent.AgentAndIPMIToolDriver)
doesn't have a console interface. It should be using IPMITools'
IPMIShellinaboxConsole().

Change-Id: I780ff2df9ed1d673fa5f124efb73ca3ecd945c85
Closes-Bug: #1359466