enhance Inflector  helper with ascii function

closes #364 

Edit: 
Seems to me that transliteration without PECL or the new Transliterator class (PHP >= 5.4), is something that a simple array won't do.

I think is ok on the first round, but if we wish to adopt transliteration the right way, we should consider some good rework on this matter.

References:

https://drupal.org/project/transliteration
http://php.net/manual/es/transliterator.transliterate.php
https://doc.wikimedia.org/mediawiki-core/master/php/html/UtfNormal_8php_source.html