Add external links for tasks with plugin api

app/Core/Http/Client.php

@@ -33,6 +33,19 @@ class Client extends Base
      */
     const HTTP_USER_AGENT = 'Kanboard';
 
+    /**
+     * Send a GET HTTP request
+     *
+     * @access public
+     * @param  string     $url
+     * @param  string[]   $headers
+     * @return string
+     */
+    public function get($url, array $headers = array())
+    {
+        return $this->doRequest('GET', $url, '', $headers);
+    }
+
     /**
      * Send a GET HTTP request and parse JSON response
      *

app/Core/Http/Response.php

@@ -68,11 +68,12 @@ class Response extends Base
      *
      * @access public
      * @param  string   $url   Redirection URL
+     * @param  boolean  $self  If Ajax request and true: refresh the current page
      */
-    public function redirect($url)
+    public function redirect($url, $self = false)
     {
         if ($this->request->getServerVariable('HTTP_X_REQUESTED_WITH') === 'XMLHttpRequest') {
-            header('X-Ajax-Redirect: '.$url);
+            header('X-Ajax-Redirect: '.($self ? 'self' : $url));
         } else {
             header('Location: '.$url);
         }