Zeroed the fridge state on initialization.

Change-Id: Ie9bd085211eb4664f124e739ef5148cc4dd5d1bb
diff --git a/frc971/control_loops/fridge/fridge.cc b/frc971/control_loops/fridge/fridge.cc
index 9533ddf..9fbd87c 100644
--- a/frc971/control_loops/fridge/fridge.cc
+++ b/frc971/control_loops/fridge/fridge.cc
@@ -285,6 +285,8 @@
       right_elevator_offset_ = -position->elevator.right.encoder;
       left_arm_offset_ = -position->arm.left.encoder;
       right_arm_offset_ = -position->arm.right.encoder;
+      elevator_loop_->mutable_X_hat().setZero();
+      arm_loop_->mutable_X_hat().setZero();
       LOG(INFO, "Initializing arm offsets to %f, %f\n", left_arm_offset_,
           right_arm_offset_);
       LOG(INFO, "Initializing elevator offsets to %f, %f\n",