Update loading code to work with composer

Change-Id: Ic8d63f197a3d409871ee886e3716f607ab2446a9
Do not require standalone builds for now, as they are broken and cannot be fixed yet

First need to have Wikibase Database also on packagist

Change-Id: I1ed1dc5e95b81bfab81841f8e5d3ba493fb84c85