Finding data nodes in choices and cases.

Feature was rewritten. It is no more taken into account if schemas for data
nodes at the same level are in the same case for concrete choice. This check should be done in system which takes Json as input

Change-Id: I12e9d2dd9bba21e5ec59a6864a41c4b82cb4f43f
Signed-off-by: Jozef Gloncak <jgloncak@cisco.com>