Break out the CIM class to avoid duplication

Before this patch we had 7 identical copies of the CIM class. Now it's
in its own module.

More de-duplication to come.

Change-Id: I598224020e50e8ec63584333dc080d34a2407cde
diff --git a/frc971/control_loops/python/BUILD b/frc971/control_loops/python/BUILD
index 897738a..ede85c0 100644
--- a/frc971/control_loops/python/BUILD
+++ b/frc971/control_loops/python/BUILD
@@ -3,6 +3,7 @@
 py_library(
   name = 'controls',
   srcs = [
+    'cim.py',
     'control_loop.py',
     'controls.py',
     'polytope.py',