Receive signal properties from the backend

[ozancaglayan]

Receive signal characteristics from the Python backend before generating the UI, e.g. the backend should send sth like:

{type: 'eeg',
 channel_count: 14,
 channel_names: ["P7", "P8", "O2",...],
 ..
 ..
}

and the UI should parse this and generate the relevant realtime plot according to this.