Add a delay before asteroid strikes

[albrow]

Right now, the asteroid strike animation plays immediately after pressing the "Deploy" button. It would be more exciting and more intuitive if it triggered on a short delay. This would make it so that G.R.O.V.E.R. reads the safe_direction from the data point and then the asteroid strikes.

The delay would likely need to be configured for each level. This change might also require moving asteroid warnings into State as opposed to being a property of each level.