Skip tests for ZF-11344 because the feature is not available in PHP 5.4+

There is a bug in PHP - [#63450](https://bugs.php.net/bug.php?id=48147) related to [bug in glibc](http://sourceware.org/bugzilla/show_bug.cgi?id=13541).

These make the feature [ZF-11344](http://framework.zend.com/issues/browse/ZF-11344) not available since PHP 5.4. This is not a big problem, because the faulty state is handled properly in the filter - it throws an exception if the ```iconv()``` or ```htmlentities()``` returns empty string or false.

Similar test skip is also in zf2:
https://github.com/zendframework/zf2/pull/1162/files