Replace submodule url reference from relative to absolute

Upstream Gerrit uses relative paths to referenced core plugins.
These reference do not work for our fork of Gerrit.  To fix this
we need to change the URL references from relative to absolute paths.
We've done this every time we need to create new branches:
 - I570ea60dbf34bfb65c
 - I0b4a4482f6e558ad8f

More info about this work around can be found here:
  https://code.google.com/p/gerrit/issues/detail?id=2517

Change-Id: I075f327146dfc5484ffdcbac11a87af178b557b2

.gitmodules

@@ -1,34 +1,34 @@
 [submodule "plugins/commit-message-length-validator"]
 	path = plugins/commit-message-length-validator
-	url = ../plugins/commit-message-length-validator
+	url = https://gerrit.googlesource.com/plugins/commit-message-length-validator
 	branch = .
 
 [submodule "plugins/cookbook-plugin"]
 	path = plugins/cookbook-plugin
-	url = ../plugins/cookbook-plugin
+	url = https://gerrit.googlesource.com/plugins/cookbook-plugin
 	branch = .
 
 [submodule "plugins/download-commands"]
 	path = plugins/download-commands
-	url = ../plugins/download-commands
+	url = https://gerrit.googlesource.com/plugins/download-commands
 	branch = .
 
 [submodule "plugins/hooks"]
 	path = plugins/hooks
-	url = ../plugins/hooks
+	url = https://gerrit.googlesource.com/plugins/hooks
 	branch = .
 
 [submodule "plugins/replication"]
 	path = plugins/replication
-	url = ../plugins/replication
+	url = https://gerrit.googlesource.com/plugins/replication
 	branch = .
 
 [submodule "plugins/reviewnotes"]
 	path = plugins/reviewnotes
-	url = ../plugins/reviewnotes
+	url = https://gerrit.googlesource.com/plugins/reviewnotes
 	branch = .
 
 [submodule "plugins/singleusergroup"]
 	path = plugins/singleusergroup
-	url = ../plugins/singleusergroup
+	url = https://gerrit.googlesource.com/plugins/singleusergroup
 	branch = .