Implement a secondary status

[izzy]

A secondary status is needed to enable notices like "open for all", "be right back"(see Bytespeicher/Bytebot#12) or "members only".

I propose this status is set inside the JSON on state.message.

Examples:

3 devices connected | open for all
3 devices connected | be right back
3 devices connected | members only

[Chaos99]

See pull request #24 . Breaks api, but might be backwards compatible