For reference, here is my solution:

def move(self, motion): # Do not change the name of this function

    # ADD CODE HERE
    alpha = float(motion[0]) + random.gauss(0.0, self.steering_noise)
    d = float(motion[1]) + random.gauss(0.0, self.distance_noise)

    beta = tan(alpha) * d / self.length
    new_orientation = (self.orientation + beta)
    new_orientation %= 2 * pi

    if abs(beta) < 0.001:
        new_x = self.x + d * cos(self.orientation)
        new_y = self.y + d * sin(self.orientation)
    else:
        R = d / beta
        cx = self.x - R * sin(self.orientation)
        cy = self.y + R * cos(self.orientation)

        new_x = cx + R * sin(self.orientation + beta)
        new_y = cy - R * cos(self.orientation + beta)

    result = robot(self.length)
    result.set(new_x, new_y, new_orientation)
    result.set_noise(self.bearing_noise, self.steering_noise, self.distance_noise)

    return result # make sure your move function returns an instance
                    # of the robot class with the correct coordinates.

def sense(self, noisy=1): #do not change the name of this function
    Z = []

    for land in landmarks:
        bearing = atan2(land[0] - self.y, land[1] - self.x) - self.orientation
        if noisy == 1:
            bearing += random.gauss(0.0, self.bearing_noise)
        bearing %= 2 * pi
        Z.append(bearing)

    return Z #Leave this line here. Return vector Z of 4 bearings.

Note the optional parameter noisy=1 in sense and the addition of noise in calculations using random.gauss