Configurable alternative for signaling server

[Chat-Wane]

Currently, our signaling server is hosted on heroku. TODO: give the possibility to the user to configure the address himself. Also, inform how/where he can host them himself.

[Chat-Wane]

Create a signaling server that also serves the CRATE files. That way, a user can choose to use such address: www.mysignalingserver.com/index.html?youKnowNothingJohnSnow which will use the signaling server hosted on mysignalingserver.

It constitutes an alternative way to configure the signaling server without passing it as an additional argument in the address.