add convinience function to get filesystem view for app storage

lib/app.php

@@ -403,4 +403,22 @@ class OC_App{
 			include OC::$SERVERROOT.'/apps/'.$appid.'/appinfo/update.php';
 		}
 	}
+
+	/**
+	 * @param string appid
+	 * @return OC_FilesystemView
+	 */
+	public static function getStorage($appid){
+		if(OC_App::isEnabled($appid)){//sanity check
+			if(OC_User::isLoggedIn()){
+				return new OC_FilesystemView('/'.OC_User::getUser().'/'.$appid);
+			}else{
+				OC_Log::write('core','Can\'t get app storage, app, user not logged in',OC_Log::ERROR);
+				return false;
+			}
+		}else{
+			OC_Log::write('core','Can\'t get app storage, app '.$appid.' not enabled',OC_Log::ERROR);
+			false;
+		}
+	}
 }