Add delay before OcPlatform.startPresence().

Add delay before OcPlatform.startPresence().

Added a two second delay before calling OcPlatform.startPresence() on the server side.
This gives the client side ample time to have the presence listener in place for expected
good behavior.

Change-Id: I0bc63b157c756abb510c3e2fb9651c3e14503b31
Signed-off-by: Larry Sachs <larry.j.sachs@intel.com>
Reviewed-on: https://gerrit.iotivity.org/gerrit/13971
Tested-by: jenkins-iotivity <jenkins-iotivity@opendaylight.org>
Reviewed-by: George Nash <george.nash@intel.com>
Reviewed-by: Rick Bell <richard.s.bell@intel.com>