Change default runtime of jobs to be 20 minutes instead of 10

Change-Id: I0faa6e82663966fa7f1fc640902b2430e3ba4788
diff --git a/jjb/defaults.yaml b/jjb/defaults.yaml
index 1922dbd..d189c11 100644
--- a/jjb/defaults.yaml
+++ b/jjb/defaults.yaml
@@ -29,7 +29,7 @@
     archive-artifacts: ''
 
     # build timeout (minutes)
-    build-timeout: 10
+    build-timeout: 20
 
     # timed trigger defaults, crontab syntax
     # H = random value hashed by name of job