move to json config

[ghi820]

Hi,

I've been working on some additional options (like the metadata and media not sharing the same path), and looking at the config format, it's difficult to add options without being breaking...

I've prepared the changeover but missed the dev-0.10 branch (now corrected). Since the matchMetadata options and the formatStudio aren't defined except as "existing". I've included them as is.

I've also moved the GraphQL Boilerplate into a proxy function, as I had to touch all invocations anyways.

Thx for your work