Add optional Gzipped argument to jsonschema so the an argument can be passed to the model reader

[jvshields]

Is your feature request related to a problem? Please describe.
The Configuration currently does not allow to specify whether MARCS models are gzipped or not. The reader is able to read either case, but the model file associated with the quickstart notebook is unzipped so that's passed as the default for now.

Once added, the run_stardis() function should also pass in the boolean value read from there.