Fixes lstrojny#36: non-standard behavior of empty value tag in struct

Merge pull request lstrojny#39 from sagikazarmark/patch-1

Updates PHP version requirement

Merge pull request lstrojny#20 from frederikbosch/patch-1

Allow huge datasources to be parsed

Adding bugfix to the changelog

Allow HTTP transport headers to be controlled

Built-in composer

Fixing exception handling

Bugfix release

Bugfix for XmlReaderParser

0.8.1: small bugfix for Guzzle Transport