Added importing/exporting of save file to the game.
Moved loading game out to new service dedicated to do just that instead of having duplicate code for loading and importing the save game.
Merge branch 'master' into spaceMining
removed mine button when asteroid is fully mined.  added section showing what resources the player has.
Made mining actually subtract how much it costs and hide mine button when you don't have enough.
started spiking out the ships that the player can buy with the mined resources.