CameraInfoManager should register services inside node namespace

[christianrauch]

The camera_info_manager::CameraInfoManager registers the set_camera_info service inside the namespace (e.g. /{NAMESPACE}/set_camera_info) while other node services are registered inside the node namespace (e.g. /{NAMESPACE}/{NODE_NAME}/set_parameters).

It would be much more consistent if set_camera_info would also be registered in the node namespace, e.g. /{NAMESPACE}/{NODE_NAME}/set_camera_info.