add minimal test for RFC 2217 client

- add new file to MANIFEST.in
- sort entries MANIFEST.in
diff --git a/examples/rfc2217_server.py b/examples/rfc2217_server.py
index 10c47c5..c94b837 100755
--- a/examples/rfc2217_server.py
+++ b/examples/rfc2217_server.py
@@ -192,3 +192,4 @@
             logging.error(str(msg))
 
     logging.info('--- exit ---')
+