engine: set emperor name on home planet when creating new game
engine: set emperor name on home planet when creating new game

A recent change to the User class pushed the responsibility of updating
the Planet objects out of the User class. Eventually either system or
galaxy will need to own the logic for "conquering" a planet. Until that
logic is added we only have the home planet to worry about.

fretboardfreak/space,fretboardfreak/space