session: cleanup part 1

Rename core data structures. This will break compatibility for out of
tree builtin apps.

- stream_session_t to session_t
- server_rx/tx_fifo to rx/tx_fifo
- stream_session.h to session_types.h
- update copyright

Change-Id: I414097c6e28bcbea866fbf13b8773c7db3f49325
Signed-off-by: Florin Coras <fcoras@cisco.com>
diff --git a/src/vnet/session/session_debug.h b/src/vnet/session/session_debug.h
index 559f0bd..2912ae3 100644
--- a/src/vnet/session/session_debug.h
+++ b/src/vnet/session/session_debug.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017 Cisco and/or its affiliates.
+ * Copyright (c) 2017-2019 Cisco and/or its affiliates.
  * 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: