Bump xos libraries to version 4.0.0

Change-Id: I7cc0eed4930ba0948e07befd9c23b4a6e5503df1
diff --git a/requirements.txt b/requirements.txt
index bad8c6b..c91c4a8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,4 +1,4 @@
-xossynchronizer~=3.2.1
-xosapi~=3.2.1
-xoskafka~=3.2.1
+xossynchronizer~=4.0.0
+xosapi~=4.0.0
+xoskafka~=4.0.0
 etcd3==0.7.0