pkg: add a function to generate chain names

Adds a function to generate chain names for use in iptables and
ports all drivers to use that function. Also adds tests for the
said function.

utils/utils_test.go

@@ -0,0 +1,18 @@
+package utils
+
+import (
+	. "github.com/onsi/ginkgo"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("Utils", func() {
+	It("should format a short name", func() {
+		chain := FormatChainName("test", "1234")
+		Expect(chain).To(Equal("CNI-test-d404559f602eab6f"))
+	})
+
+	It("should truncate a long name", func() {
+		chain := FormatChainName("testalongnamethatdoesnotmakesense", "1234")
+		Expect(chain).To(Equal("CNI-testalongnamethat-d404559f602eab6f"))
+	})
+})