Switch to full-on build file.

I'm about to add a bunch of Getdown jiggery pokery, so we'll need all the games
and all the puzzles.
Nix unused imports.
Wired up system tray icon.
Wired up Proguard and a Getdown client build.
A bunch of crap for the Mac installer.
Route our output into a log file when run as Getdown app.
Invoke mvn and sbt in user's shell rather than directly.

Otherwise we lack the user's path &c when run as a Getdown app.