Support for user defined model python file

[rajeeja]

We currently require the file names to be of the format:

python/model_runner.py:            module_name = "{}_baseline_keras2".format(model_name)
python/model_runner.py:            module_name = "{}_baseline_pytorch".format(model_name)

this can be an input from test.sh or one of cfg- files

[rajeeja]

@j-woz we set the framework string here:

Supervisor/workflows/mlrMBO/swift$
==> grep -ri framework .
./workflow.swift:string FRAMEWORK = "keras";

[j-woz]

Setting FRAMEWORK at the workflow.swift level does get passed through, I just checked. We can make this an environment variable if you want.