Switch default dt to 5.05 ms

All new loops should be on the 5.05 ms cycle, so let's flip the default
and move old robots to explicitly specify 5 ms.

Change-Id: I2495baaf2beebb0315b068efad4e68e7eed73898
diff --git a/y2019/control_loops/python/elevator.py b/y2019/control_loops/python/elevator.py
index 480ed50..5859814 100755
--- a/y2019/control_loops/python/elevator.py
+++ b/y2019/control_loops/python/elevator.py
@@ -29,8 +29,7 @@
     kalman_q_pos=0.12,
     kalman_q_vel=2.00,
     kalman_q_voltage=35.0,
-    kalman_r_position=0.05,
-    dt=0.00505)
+    kalman_r_position=0.05)
 
 kElevatorModel = copy.copy(kElevator)
 kElevatorModel.mass = carriage_mass + first_stage_mass + 1.0