[ACS42] CLOUDSTACK-4466: Fix DHCP capability breaks in 4.2 for MidoNet

[Sheng Yang]

Hi Animesh,

Please cherry-pick the following commit from 4.2-forward branch.

commit a55c75bbd201e53f0aca3e8f8f9dee08cd132a95
Author: Dave Cahill <dcah...@midokura.com>
Date:   Tue Aug 27 11:55:49 2013 -0700

    CLOUDSTACK-4466: Fix DHCP capability breaks in 4.2 for MidoNet

    A recent code change in NetworkManager causes NullPointerExceptions
when DHCP
    capability list is null.

    The commit which made the NetworkManager change also changed the
VirtualRouter
    to not use null for the capabilitylist, but didn't make this change for
other
    network devices, causing DHCP to fail on MidoNet.

    This change also updates the MidoNet plugin to use the most recent
MidoNet API.

    Signed-off-by: Sheng Yang <sheng.y...@citrix.com>

Thanks!

--Sheng