DodoApp: Introduce password role

Auto generate passwords for PostgreSQL and MongoDB.

Change-Id: Ibd9fb900ddc8dd505c60ae4dfba73f1c951e3470
diff --git a/core/installer/app_test.go b/core/installer/app_test.go
index 0838f14..6d982a8 100644
--- a/core/installer/app_test.go
+++ b/core/installer/app_test.go
@@ -472,6 +472,11 @@
   name: "db"
   size: "10Gi"
 }]
+
+postgresql: [{
+  name: "pg"
+  size: "10Gi"
+}]
 `
 
 var dodoAppDevEnabledCue = `
@@ -558,6 +563,7 @@
 		"appId":         "",
 		"sshPrivateKey": "",
 		"username":      "",
+		"password_mongodb_db": "foo",
 	}, nil, keyGen)
 	if err != nil {
 		for _, e := range errors.Errors(err) {