Set PYTHONPATH for old control loops

Running them doesn't get you the right files (namespace issues at
least), but at least they kind of work.

Change-Id: I69faa943d4db14c29bdaa6abb035f6f34ca5244d
diff --git a/y2014/control_loops/update_arm.sh b/y2014/control_loops/update_arm.sh
index c4c1ab9..c941db9 100755
--- a/y2014/control_loops/update_arm.sh
+++ b/y2014/control_loops/update_arm.sh
@@ -2,6 +2,8 @@
 #
 # Updates the arm controllers (for both robots).
 
+export PYTHONPATH=../../frc971/control_loops/python
+
 cd $(dirname $0)
 
 ./python/arm.py fridge/arm_motor_plant.cc \