Wip/martyn/u boot installer

Jenkinsfile

@@ -613,10 +613,13 @@ buildCandidates.each { name, arch ->
 }
 
 /* Add installer */
-println("buildOnlyList")
-println(buildOnlyList)
-if (buildOnlyList.containsKey('installers')) {
-  println("Got installers")
+if (buildOnlyList) {
+  if (buildOnlyList.containsKey('installers')) {
+    first_pass << [("installers"):
+        buildInstallers(installers)
+    ]
+  }
+} else {
   first_pass << [("installers"):
       buildInstallers(installers)
   ]