Update git submodules

* Update plugins/replication from branch 'master'
  to 920879c63252ce78daab0baeef60b2eb25e828c1
  - Extract out FakeExecutorService into a separate class
    
    FakeExecutorService is used in more than one test and
    thus deserves to be a separate class.
    
    Change-Id: I4b127e1e7286b68b837c07757b4946d848389134
    
diff --git a/plugins/replication b/plugins/replication
index d4242a4..920879c 160000
--- a/plugins/replication
+++ b/plugins/replication
@@ -1 +1 @@
-Subproject commit d4242a4d6dd0e8d01ac1436e9daa7d63caa507f3
+Subproject commit 920879c63252ce78daab0baeef60b2eb25e828c1