Fixed incorrect concatenation of responses.

Fixed incorrect concatenation of responses.

As part of this work, a bug was fixed in the function HandleAggregateResponse where
responses were not being concatenated correctly.
This fixes a ToDo-CA task (TA4298).

Change-Id: I981947c2d64759d1850e093ecf5c069bc8c9106a
Signed-off-by: Doug Hudson <douglas.hudson@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/333
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: Yamin Al-Mousa <yamin.s.al-mousa@intel.com>
Reviewed-by: Sashi Penta <sashi.kumar.penta@intel.com>