tweak settings passwords a bit

admin/js/users.js

@@ -54,12 +54,16 @@ $(document).ready(function(){
 		input.focus();
 		input.keypress(function(event) {
 			if(event.keyCode == 13) {
+				if($(this).val().length>0){
 					$.post(
 						OC.filePath('admin','ajax','changepassword.php'),
 						{username:uid,password:$(this).val()},
 						function(result){}
 					);
 					input.blur();
+				}else{
+					input.blur();
+				}
 			}
 		});
 		input.blur(function(){