Bug when starting without config file. Before, one would be created.

Hi @Xeor,
sorry for flooding you with pull requests. This commit fixes a bug when
starting with no config file, either in $HOME/.taggo.cfg or in the taggo
folder.

I changed the behaviour a bit so that we assume that, if we don't have a
config file in the taggo directory, we create one in $HOME/.taggo.cfg
and use it instead.