IloVirtualMediaIscsi deploy driver

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

Change-Id: I98f47ed6082a3a28fce3148f6d5177cdb5c61881
Implements: blueprint ironic-ilo-virtualmedia-driver
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