#308 linux: use xdg directory specification

[Ricardo Mones]

Original request made at Debian BTS: http://bugs.debian.org/696851

Database and initialization file are saved directly in $HOME folder as regular files. This may confuse some users.
Would be nice if these could be saved under XDG mandated directories, see http://wiki.debian.org/XDGBaseDirectorySpecification

Thanks in advance,