update cadvisor to v0.31.0

vendor/github.com/pquerna/ffjson/fflib/v1/buffer_nopool.go

@@ -0,0 +1,11 @@
+// +build !go1.3
+
+package v1
+
+// Stub version of buffer_pool.go for Go 1.2, which doesn't have sync.Pool.
+
+func Pool(b []byte) {}
+
+func makeSlice(n int) []byte {
+	return make([]byte, n)
+}