Add Turret BUILD and turret.py

Create turret.py based on the 2019 season's wrist, and turret/BUILD in the superstructure.

Change-Id: If4369697fc1dc8a01740a50b90d9ae5d2491a476
diff --git a/y2020/control_loops/python/BUILD b/y2020/control_loops/python/BUILD
index 492326b..2d1af66 100644
--- a/y2020/control_loops/python/BUILD
+++ b/y2020/control_loops/python/BUILD
@@ -81,6 +81,21 @@
     ],
 )
 
+py_binary(
+    name = "turret",
+    srcs = [
+        "turret.py",
+    ],
+    legacy_create_init = False,
+    restricted_to = ["//tools:k8"],
+    deps = [
+        ":python_init",
+        "//external:python-gflags",
+        "//external:python-glog",
+        "//frc971/control_loops/python:angular_system",
+        "//frc971/control_loops/python:controls",
+    ],
+)
 
 py_library(
     name = "python_init",