Fix ephemeral devices on LVM don't get mkfs'd

Fixes bug 1083424

Updated imagebackend to run the necessary callback conditionally
based on whether LVM is configured for use and ephemeral_size is
defined. The callback function was updated not to invoke qemu-img
for LVM, since the ephemeral disk is already present/created via
LVM. Lastly, the mkfs call had to be changed to be run as root,
since we are dealing with raw devices.

Change-Id: Ieb1febb0ea086f8e5063d92ca376d349fcd43a43
Fix Network object encoding issue when using qpid

When creating network via REST API will throw the exception
"CodecException: no encoding for
<nova.db.sqlalchemy.models.Network object at 0x4a8ea10>".
It only occurs when using qpid.
Fix this issue through using jsonutils.to_primitive method.

Fix bug 1143584.

Change-Id: I833aef451f8e3d5eaa246c19d67b2474a9d36910
Merge "Fix Network object encoding issue when using qpid"
Merge "Fix ephemeral devices on LVM don't get mkfs'd"