UI : GameScreen : Upgrade Buttons

[theRemix]

2 Upgrade buttons will always be visible by default, displaying the art asset and the cost.

https://projects.invisionapp.com/share/ZJFJT4ZBAV4#/screens/275910453

Upgrades should be in a disabled or enabled state.
If the player has enough money to purchase the upgrade, it will be enabled and is clickable.
else it is disabled and clicking it does nothing.

The UI App should have a class, or some importable object of Upgrades available, example:

export default const upgrades = {
    1 : {
        "id" : 1,
        "name" : "axe",
        "cost" : "200"
    }, ...
} 

https://github.com/GomaGames/transmission/wiki/Upgrades