Small Fixes

Fixed the typo on "Max His Master's" to become "Max With His Master's"

Added ResourceTower.png (because I somehow didn't before)

Changed the StickTower image to be Bryan's standardTower.gif

Shortened some code in GameScreen.java

Added a temporary notification message for when the user tries to place
a tower and does not have enough resources. Placing a tower or pressing
"Done" removes this notification.