fixing the argparser return vals

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
update the entity dict but not through optional kwargs

Signed-off-by: Prasanna Santhanam <tsp@apache.org>
CLOUDSTACK-989: marvin.jsonHelper deserialization results in unfilled attributes

marvin:jsonHelper.py deserializes the entire object into entity.entity field
when 'entity' is present as an attribute in the response and failing to fill in
other attributes in the response class of entity.

Signed-off-by: Prasanna Santhanam <tsp@apache.org>