Change the name of the configuration file

Change the name of the configuration file

The reason for this is that the Apache mod_wsgi sets the current
directory of WSGI processes to $HOME and on our server $HOME/.config
is a directory. Instead of changing the working directory of WSGI
processes (which I don't know how to configure), I prefer to use a
different (non-colliding) file name: .coffee.conf. Having the
configuration file outside of the source directory has the advantage
that running "git clean -fx" in that directory does not delete the
configuration, which cannot be easily recovered (our Slack history is
limited).