Merge branch 'release-0.27.0' into develop

* release-0.27.0:
  Bumping version to 0.27.0
  Bump jmespath version to 0.2.0
Fix the StackPolicyURL param.
Updating models to latest versions.
Bumping version to 0.28.0
Merge branch 'release-0.28.0'

* release-0.28.0:
  Bumping version to 0.28.0
  Updating models to latest versions.
  Fix the StackPolicyURL param.