Client-only Mode

[dsc]

It's presently a huge pain to run Limn as a fully static, client-only application, despite the fact that it's mostly there.

• Data is already stored as flat files by default, though server endpoints will recursively descend into directories searching for it.
• /datasources/all aggregates the contents of var/data/datasources. Providing a tool to generate a datasources.json file would fix this.
• DataSources should be able to be defined in the client UI so you could get started without editing any files.

That's off the top of my head, but I think that's it.