Create version without Socket.io bindings

[pwolaq]

Create basic version without Socket.io binding, as it is not used by everyone and will reduce file size.

Another solution would be to move binding to another file and treat it as extension.

[StefansArya]

Actually you could use Broadcast Channel.

But if you prefer a library that support for older browser, you could use this.
It does fallback to SharedWorker or LocalStorage if the browser didn't support it.

@brianreavis Btw, can you put a link to this repository on the readme?