added unbound to external deps

external/unbound/libunbound/python/doc/examples/example1a.rst

@@ -0,0 +1,26 @@
+.. _example_resolve_name:
+
+==============================
+Resolve a name
+==============================
+
+This basic example shows how to create a context and resolve a host address (DNS record of A type).
+
+::
+
+	#!/usr/bin/python
+	import unbound
+	
+	ctx = unbound.ub_ctx()
+	ctx.resolvconf("/etc/resolv.conf")
+	
+	status, result = ctx.resolve("www.google.com")
+	if status == 0 and result.havedata:
+		print "Result.data:", result.data.address_list
+	elif status != 0:
+		print "Resolve error:", unbound.ub_strerror(status)
+
+In contrast with C API, the source code is more compact while the performance of C implementation is preserved. 
+The main advantage is that you need not take care about the deallocation and allocation of context and result structures; pyUnbound module do it automatically for you. 
+
+If only domain name is given, the :meth:`unbound.ub_ctx.resolve` looks for A records in IN class.