ModifiedNode instantiation improvement.

Every instance of ModifiedNode will contain children with hash map instance based on Modified Node ordering. Now if ModifiedNode
will cary Ordered Children LinkedHashMap will be used otherwise ordinary HashMap will be used. This should improve performance
during validation process.

Change-Id: I83dfe70a02ca5f4a6a25c4b5ebe38debad16e46b
Signed-off-by: Lukas Sedlak <lsedlak@cisco.com>
Merge "ModifiedNode instantiation improvement."