Set back libxml_disable_entity_loader state after use

Forward port of 22e7ca04bc4c132969b1cef135bc25140b37b162 from stable6 to master
Merge pull request #81 from owncloud/libxmlentitystateresetafteruse

Set back libxml_disable_entity_loader state after use
PhpZipStream updated to work properly on php 5.3 - see https://github.com/owncloud/core/pull/3439#issuecomment-37670462
Merge pull request #82 from owncloud/update-zip-streamer

PhpZipStream updated to work properly on php 5.3 - see https://github.co...
Remove outdated and unused XML Parsing library

This library is actually not used anywhere in the code and is
vulnerable against XXE.

According to the commit log this seems to have been used for MDB2, this
library hasn’t been touched since more than 2 years.
Merge pull request #86 from owncloud/remove-outdated-library

Remove outdated and unused XML Parsing library
update composer packages and update to dbal 2.4.2