Add isUri function, better ZF2 integration and new VirtEasy class

isUri checks if a given string is a valid URI

Improve ZF2 integration by add all available classes to
autoload_classmap.php.

Add VirtEasy class to help you using EasyRdf library. EasyRdf is a
PHP library designed to make it easy to consume and produce RDF.
VirtEasy uses Virtuoso class to get the data and interact with the
store and EasyRdf to play around with the received data.