Bug 225 - added support for depth RESTCONF parameter in URI

Modified RestconfImpl to prune the resulting ComositeNode tree
based on the depth parameter, if specified.

A depth of 1 retrieves just the target resource and no children. This is
a way to determine if the resource exists. A depth of 2 retrieves the
target resource and just its direct children - any child container would
be empty.

Change-Id: I44d99f9886e3837a1bb13eda84aec3c4cc6b21ae
Signed-off-by: tpantelis <tpanteli@brocade.com>
Merge "Bug 225 - added support for depth RESTCONF parameter in URI"