allow to get the display name from an abitrary user

lib/public/user.php

@@ -56,8 +56,8 @@ class User {
 	 * @brief get the user display name of the user currently logged in.
 	 * @return string display name
 	 */
-	public static function getDisplayName() {
-		return \OC_USER::getDisplayName();
+	public static function getDisplayName($user=null) {
+		return \OC_USER::getDisplayName($user);
 	}
 	
 	/**

lib/user.php

@@ -350,8 +350,10 @@ class OC_User {
 	 * @brief get the display name of the user currently logged in.
 	 * @return string uid or false
 	 */
-	public static function getDisplayName() {
-		if( isset($_SESSION['display_name']) AND $_SESSION['display_name'] ) {
+	public static function getDisplayName($user=null) {
+		if ( $user ) {
+			return self::determineDisplayName($user);
+		} else if( isset($_SESSION['display_name']) AND $_SESSION['display_name'] ) {
 			return $_SESSION['display_name'];
 		}
 		else{