Fix whitespace username

lib/user.php

@@ -120,7 +120,7 @@ class OC_User {
 			return false;
 		}
 		// No empty username
-		if( !$uid ){
+		if(trim($uid) == ''){
 			return false;
 		}
 		// Check if user already exists

settings/js/users.js

@@ -126,7 +126,7 @@ $(document).ready(function(){
 	$('#newuser').submit(function(event){
 		event.preventDefault();
 		var username=$('#newusername').val();
-		if(username == '') {
+		if($.trim(username) == '') {
 			alert('Please provide a username!');
 			return false;
 		}