enable ceph-deploy configuration files

This PR is gigantic. Sorry.

And all it does is to provide a way to locate the ceph-deploy config file creating one for the user if it does not exist in either $HOME/.cephdeploy.conf nor $CWD/cephdeploy.conf

*Nothing* is calling these helpers yet though, they are there to provide the necessary harness once the new configuration options are needed.

Unit tests were added and the ceph.py file was moved to conf/ceph.py. That is the reason why so many changes: all imports had to change.