Add stuff we have so far to wpilib_interface.

Change-Id: If880956affacf585d12f4df799f3c6426cf677f1
diff --git a/y2016/control_loops/drivetrain/BUILD b/y2016/control_loops/drivetrain/BUILD
index 1150426..cfdcf42 100644
--- a/y2016/control_loops/drivetrain/BUILD
+++ b/y2016/control_loops/drivetrain/BUILD
@@ -60,6 +60,7 @@
   deps = [
     ':polydrivetrain_plants',
     '//frc971/control_loops/drivetrain:drivetrain_config',
+    '//frc971:shifter_hall_effect',
     '//y2016:constants',
   ],
 )