Remove duplicated method in mock_key_mgr

The method _generate_key_id was duplicated in
nova/keymgr/mock_key_mgr.py

This patchset removes one of the duplicates.

Change-Id: Idb30fca9d392fe5f5b4063ba1b22a967329987f6
Add block device mapping objects implementation

This patch introduces the basic block device mapping objects and list
classes and adds tests for the basic functionality.

Related to blueprint: icehouse-objects

Change-Id: I24ace8f730978d2e7046986f212c34604c7b7f20
Move compute API is_volume_backed to BDM objects

This patch makes is_volume_backed_instance use block device objects. It
is a first step towards using new-world BDM objects in code paths that
do not need to send them over RPC.

It will also be the way to go forward when getting rid of legacy block
device usage anywhere outside of the v2 API.

This patch also moves some of the uses of the compute API
_get_bdm_image_metadata method over the block device objects list class
root_metadata method, which has some of the code duplicated. The
duplication is however necessary, since we still need to be able to deal
with old-style block devices until we deprecate the v2 API.

Related to blueprint: icehouse-objects
Related to blueprint: clean-up-legacy-block-device-mapping

Change-Id: Ibfb120ccdeb89291059ffe355957f386aec75007
Merge "Remove duplicated method in mock_key_mgr"
Merge "Add block device mapping objects implementation"
Merge "Move compute API is_volume_backed to BDM objects"