Interim commit.
Modified code so that MotherShip isn't removed when destroyed.

Game is over at this point so we might as well leave the MotherShip in
place.
Merge branch 'issue38' into develop
Merge branch 'develop' of git@github.com:gsnorton/CS-547-Project-Two.git
into develop

Modified what happens when the MotherShip health reaches zero.