Make python things work in the sandbox

Everything seems to be plotting now, and graph_edit draws again.

Change-Id: I2aceb13577c0d7529e3169f89e2d0c71612f3a47
diff --git a/y2018/control_loops/python/graph_edit.py b/y2018/control_loops/python/graph_edit.py
index dde67c5..e2b0412 100644
--- a/y2018/control_loops/python/graph_edit.py
+++ b/y2018/control_loops/python/graph_edit.py
@@ -1,3 +1,5 @@
+#!/usr/bin/python3
+
 from __future__ import print_function
 import os
 import basic_window