Got a basic implementation of persistence working (#66)
- When the Grid object is instntiated, it checks to see if we have a previous state
- If we do, it goes through and constructs a request to Redis to get those values and puts them in the right places in the grid
- Otherwise, it sets a flag so that the next time the grid is instantiated, it will know to load the state from Redis
- Currently, storing individual clicks to the grid is not async (which will be addressed in the next couple of commits)