Support Bulgarian in toAscii

The “proper” bulgarian translitaration should encode ь to y [1],
However, since its not really that important to understand the actual
word, very rearly used and breaks compatibility with Russian, it might
be best to just leave it be, since Russian is a much larger torget.

[1] http://en.wikipedia.org/wiki/Romanization_of_Bulgarian

tests/Stringy/CommonTest.php

@@ -331,6 +331,7 @@ abstract class CommonTest extends PHPUnit_Framework_TestCase
             array('numbers-1234', 'numbers 1234'),
             array('perevirka-ryadka', 'перевірка рядка'),
             array('bukvar-s-bukvoy-y', 'букварь с буквой ы'),
+            array('barzi-i-yarostni', 'бързи и яростни'),
             array('foo:bar:baz', 'Foo bar baz', ':'),
             array('a_string_with_underscores', 'A_string with_underscores', '_')
         );