Add a page to display completed tasks and add the completion date column for tasks

models/base.php

@@ -17,7 +17,7 @@ require __DIR__.'/schema.php';
 abstract class Base
 {
     const APP_VERSION = 'master';
-    const DB_VERSION  = 1;
+    const DB_VERSION  = 2;
     const DB_FILENAME = 'data/db.sqlite';
 
     private static $dbInstance = null;