Add Client Server Handshake

[rmorshea]

Current Situation

Currently, as soon as the websocket connects, the client and server start communicating layout updates/events. This does not allow any extra information to be sent. For example, the client and server could confirm that they are compatible by inspecting their versions.

Proposed Actions

Now that we have message types, we can define and handle an initial set of handshake messages between the server and client. These two handshake messages could communicate version information as well as configuration options (e.g. whether to display server logs in the client and visa versa).