Release v0.18.0

Encompass multiple upstream changes

All changes are listed below:

• Schema: (BREAKING): Add deprecation object to ISOs and deprecate deprecated
  Upstream changelog entry
• Doc: Remove note about missing vSwitch connection
• Schema: (BREAKING): Iso type is nullable now
• Doc: Specify unit of cookie_lifetime as seconds
• Doc: Clarify that resources are detached during server deletion
• Schema: (BREAKING): load_balancer_algorithm now has a default and is therefore optional
• Schema: (BREAKING): Name is optional in UpdateVolumeRequest
• Meta: Remove hack for int64 IDs
• Schema: (BREAKING): Remove sort by progress for action endpoints
  Upstream changelog entry