Add windows support

[charlespwd]

Currently the config file is set to be located in either $XDG_CONFIG_HOME/habitica/auth.cfg or $HOME/.config/habitica/auth.cfg.

Some people use windows but I have no idea where I should put the config files. Suggestions welcome :)

[hrueschwein]

what about $USER/AppData/Roaming?

[moiSentineL]

%appdata%

from: https://superuser.com/a/775943