Netconf is using the XML packages in config-util extensively,
so we should package it separately from odl-config-core to express
the dependency correctly.
JIRA: NETCONF-508
Change-Id: Id3f0b88f1ebcb9bd41292ecb948e15e6ffcde49d Signed-off-by: Robert Varga <robert.varga@pantheon.tech>