[vsphere] check for string true/false instead of boolean

closes #2857
Release 1.22.0
[google|compute] Add Region tests
Enabled :path_style for Google Cloud Storage for allowing CNAME buckets
[google|compute] Update Images support

- Add missing "Image" properties
- Add "ready?" method to model
- Add "destroy" method to model
- Use "Operation" instead of the "backoff_if_unfound" method when inserting an "Image"
Merge pull request #2862 from frodenas/gce_images

[google|compute] Update Images support
Merge pull request #2872 from asanalabs/master

[google|storage] Enabled :path_style for Google Cloud Storage for allowing CNAME buckets
Merge pull request #2869 from frodenas/gce_region_tests

[google|compute] Add Region tests
[google|compute] Improve Disks support

- Add missing "Disk" properties
- Remove unnecessary property aliases
- Use "Operation" instead of the "backoff_if_unfound" method when
  inserting a "Disk" or "Snapshot"
- When destroying a "Disk" asyncronous return the "Operation" model instead
  of the raw operation response
- Add "list_aggregatted_disks" request
- If zone is not set on "all" and "get" methods, use the list aggregated
  disks request (1 API call) instead of fetching all zones
- Fix a bug when inserting a snapshot (description was not merged at the
  body request)
- Fix tests