Added a FileChooser to the add pack for later

Signed-off-by: Dalton Pelc <daltonjpelc@gmail.com>
Merge branch 'dev' of github.com:TechnicPack/Spoutcraft-Launcher into dev
Merge branch 'dev' of github.com:TechnicPack/Spoutcraft-Launcher into dev
Custom Directories!