* added start methods for OrderedLeafSet
* modified classes that use NormalizedNodeStreamWriter to use
startOrderedLeafSet when needed.
Change-Id: I890a338313229b1600adcf5ac2ef1c8b440a220d Signed-off-by: Jan Hajnar <jhajnar@cisco.com> Signed-off-by: Robert Varga <robert.varga@pantheon.sk>