Only mount app data volumes if localstorage is used

src/sftp.js

@@ -40,7 +40,7 @@ function rebuild(options, callback) {
 
         let dataDirs = [];
         result.forEach(function (app) {
-            if (!app.dataDir) return;
+            if (!app.manifest.addons['localstorage']) return;
 
             if (options.ignoredApps && options.ignoredApps.indexOf(app.id) !== -1) {
                 debug(`Ignoring volume for ${app.id}`);
@@ -49,7 +49,7 @@ function rebuild(options, callback) {
 
             dataDirs.push({
                 hostDir: app.dataDir || path.join(paths.APPS_DATA_DIR, app.id, 'data'),
-                // /data is required since this is where the localstorage data would be in APPS_DATA_DIR
+                // FIXME data/ prefix can be dropped if sftp addon code is changed
                 mountDir: `/app/data/${app.id}/data`
             });
         });