add auto update feature

app/Http/Controllers/UpdateController.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Laraspace\Http\Controllers;
+
+use Illuminate\Http\Request;
+use Laraspace\Space\Updater;
+
+class UpdateController extends Controller
+{
+    public function update(Request $request)
+    {
+        set_time_limit(600); // 10 minutes
+
+        $json = Updater::update($request->alias, $request->installed, $request->version);
+
+        return response()->json($json);
+    }
+}