Object storage

don't merge before https://github.com/owncloud/3rdparty/pull/99 is in 3rdparty
- [ ] https://github.com/owncloud/3rdparty/pull/99 moves rackspace to 3rdparty, but files_external also provides it, causing tests to fail ...
- [x] swift test should create a new container on every test run and delete it afterwards
It is a trystack account I created. trystack is explicitly set up for testing only: http://trystack.org/ all data will be wiped periodically (24h). So this does seem to make it a nice test environment. That is until we have a real openstack server up and running ... but I want this tested in all test runs ... hence the hardcoded account.