Minor improvements to scaling API

[andrewlee94]

trafficstars

Fixes None

Summary/Motivation:

Based on initial demonstrations of the new scaling tools, a few minor improvements have been suggested.

Changes proposed in this PR:

• Change API of call_submodel_scaler_method to take submodel object instead of string name.

Legal Acknowledgement

By contributing to this software project, I agree to the following terms and conditions for my contribution:

1. I agree my contributions are submitted under the license terms described in the LICENSE.txt file at the top level of this directory.
2. I represent I am authorized to make the contributions and grant the license. If my employer has rights to intellectual property that includes these contributions, I represent that I have received permission to make contributions and grant the required license on behalf of that employer.