Added Openstack Swift support

[Pyjou]

Hello @Lucretius ,
I added direct Openstack Swift support as storage backend.
If you want to use it, that the configuration needed:

"swift_storage":{
        "auth_url": "Keystone Endpoint",
        "username": "Keystone user",
        "api_key": "Keystone password",
        "tenant_id": "Project ID",
        "region": "Region name",
        "domain": "Domain name",
        "container": "Container name (Swift)"
   }

[maclermo]

Nice work !