Introduce Vyatta VPN agent cmd in monkey patched eventlet module

Commit [1] introduced an entry for reference vpn agent in cmd/eventlet module
so that they get monkey patched in an uniform way. This commit introduces the
same for vyatta vpn agent.

[1] I2d7081dbd4cb532332e3b66667bb8c71aa5a6658

Change-Id: Icc3c8f040bd4fbb2ad36e3d32a381a7ba7993d53
Closes-Bug: 1434337

neutron_vpnaas/cmd/eventlet/vyatta_agent.py

@@ -0,0 +1,21 @@
+# Copyright 2015 Brocade Communications System, Inc.
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+#
+
+from neutron_vpnaas.services.vpn import vyatta_agent
+
+
+def main():
+    vyatta_agent.main()