Replace uws with ws package

`uws` was deprecated by its maintainer and starts to cause more and more
problems and issue reports. So it's time to replace it and use a
maintained project instead. Lucky us, `uws` and `ws` can be used in an
identical way, without problems. To provide better performance, we
install the optional packages as well.

Signed-off-by: Sheogorath <sheogorath@shivering-isles.com>

app.js

@@ -58,7 +58,7 @@ app.use(morgan('combined', {
 
 // socket io
 var io = require('socket.io')(server)
-io.engine.ws = new (require('uws').Server)({
+io.engine.ws = new (require('ws').Server)({
   noServer: true,
   perMessageDeflate: false
 })