BUG-979: reworked data schema nodes ordering

This patch changes ordering of child nodes - nodes are ordered as they are declared in
yang file (before they were sorted in alphabetical order). This ordering is applied for
schema node builders and also for schema node instances.

Change-Id: I628d40be638fc56ee3e4e1ff9c161ab1cf88ae19
Signed-off-by: Martin Vitez <mvitez@cisco.com>
Merge "BUG-979: reworked data schema nodes ordering"