Remove PHP for now

OpenStack-SDK-PHP ( https://wiki.openstack.org/wiki/OpenStack-SDK-PHP )
belongs here instead. However, it's a WIP so we're simply going to remove
PHP OpenCloud for now.

Change-Id: I66aaeefec193c2f5f20a09c71227c4d778c4f2c5
Implements: blueprint developer-openstack-org