Fix misleading diagnostics on exception

For example,

```php
<?php
$object = new stdClass();
$object->title = 'Hello "world!"';

$form = new Phalcon\Forms\Form($object);
$form->add(new Phalcon\Forms\Element\Text("title"));
echo $form->render('title');
```

when run, it produces something like this:

```
Warning: Uncaught exception 'Phalcon\Tag\Exception' with message 'A dependency injector container is required to obtain the "escaper" service' in /home/vladimir/workspace/cphalcon/1190.php:8
Stack trace:
#0 [internal function]: Phalcon\Tag::getEscaperService()
#1 [internal function]: Phalcon\Tag::_inputField('text', Array)
#2 [internal function]: Phalcon\Tag::textField(Array)
#3 [internal function]: Phalcon\Forms\Element\Text->render(NULL)
#4 /home/vladimir/workspace/cphalcon/1190.php(8): Phalcon\Forms\Form->render('title')
#5 {main}
  thrown in /home/vladimir/workspace/cphalcon/1190.php on line 8

Fatal error: Phalcon\Tag::_inputField(): Call to undefined function self::getescaperservice() in /home/vladimir/workspace/cphalcon/1190.php on line 8
```

"Fatal error" message should not be there.