Use XPath expressions where possible.
Use XPath expressions where possible.

Many of the places where we were iterating over the node list
could be accomplished much more clearly by using XPath instead.
Update these areas to use XPath.

Signed-off-by: Chris Lalancette <60b62644009db6b194cc0445b64e9b27bb26433a@redhat.com>

ike-dai/libdeltacloud-for-cloudmodule,ike-dai/libdeltacloud-for-cloudmodule