Correctly handle strings ending in backslash in debug mode

Master copy of RestServer gets confused if string ends in backslash \
If we have function
```php
        /**
         * @url GET /backslash
         */
        function backslash() {
                return array(
                        'bck' => 'abra\\',
                        'slsh' => 'ka,dabra');
        }
```
it will return 
```javascript
{
  "bck": "abra\\","slsh":"ka,
  dabra"}
```
when it should return
```javascript
{
  "bck": "abra\\",
  "slsh": "ka,dabra"
}
```