node now also serves event information

event info is pulled from the rails backend and sent to all retail
clients upon connecting
also improved seat management: initial seat info doesn't contain any
selected attributes because at this point there can't be any selected
seats (user hasn't made any selection), grid position is only sent to
retail clients (on initial event update) because web clients get it
directly from rails
new names for the clients: webClient and retailClient

also renamed the respective namespace and improved app.js
each client class implements its own placeOrder() method
moved some client-specific stuff to the client base class

also fixed some bugs