Fix {} keepalives

[codesections]

Since #78, Flodgatt has sent an keepalive websocket message consisting of {} to inform the client that the connection is still alive. This is perfectly functional, but is slightly ugly when debugging: when looking at the message view of a websocket connection, the actual messages are mixed in with many pings as shown below

This is not much of an issue, even when debugging: it only shows up when you've selected the message pane of the relevant websocket request. This means it doesn't clutter the console or interfere with debugging any non-flodgatt features. On the other hand, it will be nice to get rid of the clutter when we can.

Fortunately, the issue has been fixed upstream, in Warp 0.2.2. Unfortunately, we're still on the last 0.1.x build of warp. Once we upgrade and deal with breaking changes (#75), should be be able to solve this issue.