Update git submodules

* Update plugins/cookbook-plugin from branch 'master'
  - Bump GWT version to 2.8-rc2
    
    Change-Id: I886c722df7515a0bab524da295b24d4e6141ec10
    
  - Bump plugin API to 2.14-SNAPSHOT
    
    Change-Id: Ie83d3215d72598b7458f520922f47b836d5c2015
    
diff --git a/plugins/cookbook-plugin b/plugins/cookbook-plugin
index 60449dd..23572e6 160000
--- a/plugins/cookbook-plugin
+++ b/plugins/cookbook-plugin
@@ -1 +1 @@
-Subproject commit 60449ddf39a533ab7184d8b9d72648c9f3505e52
+Subproject commit 23572e6c83531fceea69c1356a5e1b6753ecf0e3