BUG 1204 - exception if multiple container node occures

Container schema node + multiple data nodes ->
 exception RestconfDocumentedException is raised.
List schema node + one data node (e. g. in json is specified as container
"list-name":{} and not "list-name":[{},{}...,{}] -> this is acceptable case because
list can have even only one entry.
Leaf schema node + multiple data nodes -> special check whether at
equal objects is everytime uniqe key. If it isn't so then
RestconfDocumentedException is raised. For Json specific JsonParser was
implemented which is catch duplicity at object level an time of parsing.
For XML this duplicity name check is done during normalization phase.

Change-Id: I0b544c015bcf817e82206276bd24c783093308d6
Signed-off-by: Jozef Gloncak <jgloncak@cisco.com>