Configuration hierarchy

[MatthewHambley]

Currently configuration must be specified as an argument to the CLI. This is considered to be "per project" configuration.

We might also like to support "personal" configuration which is specified in $HOME/.stylist.py and "site" configuration in /etc/stylist.py.

This should be loaded in the order site, personal and project allowing configuration appearing later to override earlier configuration.

With this in place it is not necessarily required to specify configuration at the command line.

It is not clear if there is demand for this feature.