Update plugins to latest revisions

Update the plugins:

- commit-message-length-validator
- download-commands
- reviewnotes
- singleusergroup

to add the fix:

- Add Gerrit-PluginName in BUCK file

Change-Id: Icb0e51be909c124598e9e7d2f5d8d648dfd97a0d
diff --git a/plugins/commit-message-length-validator b/plugins/commit-message-length-validator
index 5ea4e66..c882e58 160000
--- a/plugins/commit-message-length-validator
+++ b/plugins/commit-message-length-validator
@@ -1 +1 @@
-Subproject commit 5ea4e667c22bd920ce53201016ccf63f43819c0b
+Subproject commit c882e583226d712053ad02fdee4afcfd1e4df915
diff --git a/plugins/download-commands b/plugins/download-commands
index 4c1ab53..4e978f9 160000
--- a/plugins/download-commands
+++ b/plugins/download-commands
@@ -1 +1 @@
-Subproject commit 4c1ab539a956cb3fddea9c6af1f3c07e4e522cd1
+Subproject commit 4e978f916d429ab22b0ea28d25ac87755513cc56
diff --git a/plugins/reviewnotes b/plugins/reviewnotes
index 602c430..de5eccc 160000
--- a/plugins/reviewnotes
+++ b/plugins/reviewnotes
@@ -1 +1 @@
-Subproject commit 602c430749bcbadcaa3adb27fbbfc745fef074b3
+Subproject commit de5eccc9c5477a3c504c523f39dfede35426ec8c
diff --git a/plugins/singleusergroup b/plugins/singleusergroup
index a06c582..3c59757 160000
--- a/plugins/singleusergroup
+++ b/plugins/singleusergroup
@@ -1 +1 @@
-Subproject commit a06c5827222242285737258e823f13414bb5cf97
+Subproject commit 3c5975763148a6ea2bfa867a96ba5498ae5767f2