Move App to src

- Add `use Friendica\App;` wherever needed

view/theme/vier/config.php

@@ -1,9 +1,10 @@
 <?php
+
 /**
  * Theme settings
  */
 
-
+use Friendica\App;
 
 function theme_content(App $a) {
 	if (!local_user()) {

view/theme/vier/theme.php

@@ -9,6 +9,8 @@
  * Description: "Vier" is a very compact and modern theme. It uses the font awesome font library: http://fortawesome.github.com/Font-Awesome/
  */
 
+use Friendica\App;
+
 require_once "include/plugin.php";
 require_once "include/socgraph.php";
 require_once "mod/proxy.php";