[quilt] Add helpers for debian packaging

This includes the `quilt-dpkg` configuration from the debian
new-maintainer's guide.
[installer] Automatically create .config directory

This gets rid of the errors:

cp: cannot create directory `/home/pipeep/.config/pipeep-common':
    No such file or directory
cp: cannot create directory `/home/pipeep/.config/powerline':
    No such file or directory