Making Fitting Code independent

[calcuttj]

Shyam suggests putting this all in its own repo/codebase so that we make it more portable. Users can use this without art, larsoft, etc. Don't need such heavy dependencies, don't need to use SL7 container

• Extract into its own repo
• Trim dependencies (art, CET)
• Switch configuration languages (start with json, consider others. Have a configuration interface and the specific choice of language is extendable)