Add binomial calculation and tests.

Change-Id: I7a758d098c7af53e7b719461aa5d0e8de240052d
diff --git a/frc971/control_loops/BUILD b/frc971/control_loops/BUILD
index b6b0362..6d895de 100644
--- a/frc971/control_loops/BUILD
+++ b/frc971/control_loops/BUILD
@@ -294,3 +294,19 @@
     visibility = ["//visibility:public"],
     deps = ["//frc971:python_init"],
 )
+
+cc_library(
+    name = "binomial",
+    hdrs = ["binomial.h"],
+)
+
+cc_test(
+    name = "binomial_test",
+    srcs = [
+        "binomial_test.cc",
+    ],
+    deps = [
+        ":binomial",
+        "//aos/testing:googletest",
+    ],
+)