Removed NSMessage_consumer structure.

Removed NSMessage_consumer structure.

NSMessage_consumer sturcture is for direct request to provider,
It is designed for excepted storage module.
But, consumer service should set a storage,
so, NSMessage_consumer information no need more.
Finally, NSMessage_consumer is deleted and internal logic is modified.

NSMessage_consumer is deleted.
NSStoreMessage is added for storage.
bug fix for copy NSMessage structure.
Null pointer checking logic is added.

Change-Id: I2eb9f9ed3e9921e978e85a299f342eac240635f0
Signed-off-by: KIM JungYong <jyong2.kim@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/9683
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Hun-je Yeon <hunje.yeon@samsung.com>
Reviewed-by: Uze Choi <uzchoi@samsung.com>