Update chapter 4 teleop code

Author: robot

chapter_4_codes/diff_wheeled_robot_control/scripts/diff_wheeled_robot_key

@@ -27,8 +27,6 @@
 # ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 # POSSIBILITY OF SUCH DAMAGE.
 
-import roslib
-roslib.load_manifest('turtlebot_teleop')
 import rospy
 
 from geometry_msgs.msg import Twist