Expose result_keys as a property

Allows clients to manually construct the results if they want
to do so.  Used by the CLI.
Update botocore to use dev branch of jmespath

This also required a change to the s3 page configs.  Based
on feedback, the 'or' token was replaced with '||'.
Update test with new 'or' jmespath syntax
Merge branch 'jmespath-or' into develop

* jmespath-or:
  Update test with new 'or' jmespath syntax
  Update botocore to use dev branch of jmespath
Merge branch 'expose-result-keys' into develop

* expose-result-keys:
  Expose result_keys as a property
Update EC2 model for Reserved Instances instance type modifications
Update opsworks models for new resource management features
Merge branch 'model-updates2' into develop

* model-updates2:
  Update opsworks models for new resource management features
  Update EC2 model for Reserved Instances instance type modifications
Bump jmespath dep to 0.0.3
Bumping version to 0.19.0
Merge branch 'release-0.19.0' into develop

* release-0.19.0:
  Bumping version to 0.19.0
Updating requests to 2.0.0.