Fix bug for invalid remove a context at request.

Fix bug for invalid remove a context at request.

When receive responce of getting topic information,
consumer serivce remove context manually.
But, it is the invalid way.
With this patch, consumer service does not remove manually.
Context will be removed automatically by RI layer.

Change-Id: I1278dc13bf297b95e513d364f243064b525a7083
Signed-off-by: KIM JungYong <jyong2.kim@samsung.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/13025
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Uze Choi <uzchoi@samsung.com>