VMware: boot from iso support

The code enables the VMware driver to boot from an ISO
image.

Implements blueprint vmware-iso-boot

Change-Id: I568df99d6530f898d5a1885256604cf050b33dba
Move live migration callbacks to BDM objects

This patch moves the two live migration callbacks _post_live_migration
and _rollback_live_migration to use BDM objects.

As this is the last code that was using _get_instance_volume_bdms helper
method, this patch removes it.

Part of blueprint: icehouse-objects

Change-Id: I904d8b5b58d0ee4ba5a5d836fe3f8a236793f33b
Move run_instance compute to BDM objects

This patch moves the run_instance code of the compute service to BDM
objects.

This is the last bit of compute that needed migrating to BDM objects.

Part of blueprint: icehouse-objects

Change-Id: I055651b5fd415092787d9487a69467a9bbcf073e
Remove compute API get_instance_bdms method

This method is just an unnecessary level of indirecton, now that we have
BDM objects that give us a nice API on top of db calls, so we can remove
it,

Part of blueprint: icehouse-objects
Part of blueprint: clean-up-legacy-block-device-mapping

Change-Id: I02226cfb67955b604d6bed513211ef46fb65dc69
Merge "Move live migration callbacks to BDM objects"
Merge "Move run_instance compute to BDM objects"
Merge "VMware: boot from iso support"
Merge "Remove compute API get_instance_bdms method"