Bug 981: Fixed accidental shaddowing of data in Data Change Event.

Not all Normalized DOM InstanceIdentifier has their counterpart
in Binding-Aware representation. Added explicit check to
detect mixin instance-identifiers which could lead to
incorrect deserialization into maps and shadowing parent data.

Change-Id: I66166f50c636ce0dfcd962efac7fc488da622336
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
Merge "Bug 981: Fixed accidental shaddowing of data in Data Change Event."