Bug 1761: Fixed missing module name prefix for augmentations.

Migration to more state tracking introduced regression
where module name prefix was left out for containers
and lists which were augmented, which was inconsistent
with case augmentations, which were serialized properly.

Draft draft-lhotka-netmod-yang-json-02 allows previous
behaviour (without module names for augmented items),
but that may cause changing textual representation
after conflicting augmentation is introduced,
so we opted to always report module name for top level
items of augmentation, which is also allowed from spec.

Change-Id: Icbb1b2aeed1a154a06e7f90f0dacc199a7df6bcc
Signed-off-by: Tony Tkacik <ttkacik@cisco.com>
Signed-off-by: Robert Varga <rovarga@cisco.com>