Add kokoro presubmit labels

Change-Id: I05edbb46f7c4557141bb18b9b8d654261aacdc79
diff --git a/project.config b/project.config
index 99d3a50..d7529d1 100644
--- a/project.config
+++ b/project.config
@@ -17,6 +17,8 @@
 	read = group Google-Developer
 	read = block group Anonymous Users
 	read = block group Registered Users
+	label-Presubmit = -1..+1 group mdb/kokoro
+	label-Presubmit = -1..+1 group mdb/kokoro-dedicated
 [access "refs/for/refs/*"]
 	push = group Allowed-Developers
 	push = group Google-Developer
@@ -64,6 +66,12 @@
 	value = 0 No score
 	value = +1 Looks good to me, but someone else must approve
 	value = +2 Looks good to me, approved
+[label "Presubmit"]
+	function = MaxWithBlock
+	value = -1 Fails
+	value = 0 No score
+	value = +1 Verified
+	copyAllScoresIfNoCodeChange = true
 [access "refs/for/*"]
 	addPatchSet = group Allowed-Developers
 	addPatchSet = group Google-Developer