IloVirtualMediaAgent deploy driver

This commit introduces a new deploy driver which uses iLO virtual
media to boot up proliant baremetal nodes, and uses agent to deploy
the baremetal nodes.

This patch also changes agent pxe config template slightly, so that
the names of agent ramdisk parameters generated in code and those
expected by agent ramdisk are same.

Change-Id: Ia5677dff294bc146b864bed180fbda939cf9bb38
Implements: blueprint ilo-virtualmedia-ipa