Support installation from URLs.

lib/cli.js

@@ -427,10 +427,15 @@ program
     , 'public ip for global access'
     , String
     , ip())
+  .option('--save-dir <dir>'
+    , 'where to save files'
+    , String
+    , os.tmpdir())
   .action(function(options) {
     require('./roles/storage/temp')({
       port: options.port
     , publicIp: options.publicIp
+    , saveDir: options.saveDir
     })
   })