Add basic end-to-end signing and verification tests.

dkim/tests/data/test.message

@@ -0,0 +1,8 @@
+Received: from localhost
+Message-ID: <[email protected]>
+Date: Mon, 01 Jan 2011 01:02:03 +0400
+From: Test User <[email protected]>
+To: [email protected]
+Subject: Testing
+
+This is a test message.