Refactor angular_system out of 2016 intake

Change-Id: I82272ea74b375861f8472e735fd489b431614ebe
diff --git a/y2017/control_loops/python/BUILD b/y2017/control_loops/python/BUILD
index 3f23bde..50f5584 100644
--- a/y2017/control_loops/python/BUILD
+++ b/y2017/control_loops/python/BUILD
@@ -88,6 +88,7 @@
         ":python_init",
         "//external:python-gflags",
         "//external:python-glog",
+        "//frc971/control_loops/python:controls",
         "//frc971/control_loops/python:linear_system",
     ],
 )