Merge Phil Zimmermann's libzrtp as a FreeSWITCH library

Thanks to Phil Zimmermann for the code and for the license exception
we needed to include it.

There remains some build system integration work to be done before
this code will build properly in the FreeSWITCH tree.

libs/libzrtp/test/win_ce/stdafx.cpp

@@ -0,0 +1,18 @@
+/*
+ * libZRTP SDK library, implements the ZRTP secure VoIP protocol.
+ * Copyright (c) 2006-2009 Philip R. Zimmermann.  All rights reserved.
+ * Contact: http://philzimmermann.com
+ * For licensing and other legal details, see the file zrtp_legal.c.
+ * 
+ * Nikolay Popok mailto: <chaser@soft-industry.com>
+ */
+
+
+// stdafx.cpp : source file that includes just the standard includes
+// libzrtp_test_GUI.pch will be the pre-compiled header
+// stdafx.obj will contain the pre-compiled type information
+
+#include "stdafx.h"
+
+// TODO: reference any additional headers you need in STDAFX.H
+// and not in this file