Fixed SimpleXML namespacing error

1.5.1

Fixed error with SimpleXMLElement namespacing

Updated Composer autoloading to PSR-4

Updated composer compliance to PSR-4.

Updated examples and README to reflect new autoload scheme

Added cURL support

This release brings support for cURL and a new set of documentation files.

Fixed composer.json

Fixed composer.json to allow auto-update on Packagist.org

Fixes autoloader and clean comments

This new release merges the latest pull requests (thanks to fbonzon and benedya).