* Support skip of platforms by version in tests.
Previously a remote platform could be skipped completely using the alias:
`skip/{platform}` such as `skip/rhel`
Now a specific platform version can be skipped using the alias:
`skip/{platform}{version}` such as `skip/rhel7.6`
This feature is available for platforms specified with the `--remote` option.
* Add skip by version to the docs.
* Update Shippable integration test groups.
* Update integration test group aliases.
* Rebalance AWS and Azure tests with extra group.
* Rebalance Windows tests with another group.
