refactored backend, large-wall, mobile into proper modules
As of right now, the backend logs in users, starts the round according to the rules I've set up, and manages a queue of players. more testing and debugging is necessary to continue to verify end-to-end functionality.
Timer object in Large Wall handles a simple timer display, seems to work reasonably well
Moved Timer object into utils, added an element id param to set() so that the same timer can be recycled for both round timing and prepare timing.
fixed the timer handoff on large wall
Visualization for wait queue and players now up on the backend.html, as well as backend round and prepare timers. Config parameters are also displayed (to make it easier to tweak the values).
Added another update call to the player list visualization