Update plugins to latest revisions

This change bumps up the API version to 2.8 in the pom.xml files
of the plugins:

- commit message length checker
- cookbook
- replication
- reviewnotes

Change-Id: I1842daaf89a4484a0cab713a6ef45af0c772d5b7

plugins/commit-message-length-validator

diff --git a/plugins/commit-message-length-validator b/plugins/commit-message-length-validator
index 45f347d..6eba481 160000
--- a/plugins/commit-message-length-validator
+++ b/plugins/commit-message-length-validator
@@ -1 +1 @@
-Subproject commit 45f347d0e258ef7b871b046bfa96b9f902063b10
+Subproject commit 6eba481780ec60391f65b86222a7888e3a41e373

plugins/cookbook-plugin

diff --git a/plugins/cookbook-plugin b/plugins/cookbook-plugin
index 5ee3f28..a42ccfb 160000
--- a/plugins/cookbook-plugin
+++ b/plugins/cookbook-plugin
@@ -1 +1 @@
-Subproject commit 5ee3f28739700e97b91231a2b694f3ba78065e86
+Subproject commit a42ccfbd7c71ffa36d30015d0da20f9e816a3691

plugins/replication

diff --git a/plugins/replication b/plugins/replication
index fa66d17..2ce2636 160000
--- a/plugins/replication
+++ b/plugins/replication
@@ -1 +1 @@
-Subproject commit fa66d17b1d6ed3266d0e9061a852fc530ec2ea73
+Subproject commit 2ce26361617909ea3d91d50ced0e8289f7ec342f

plugins/reviewnotes

diff --git a/plugins/reviewnotes b/plugins/reviewnotes
index 9905f7a..6874243 160000
--- a/plugins/reviewnotes
+++ b/plugins/reviewnotes
@@ -1 +1 @@
-Subproject commit 9905f7af6c4e258365413a03f092898b167ea25a
+Subproject commit 68742432107edeead1b5b9a86f769c60023ea0ea