Path to modeshape config

https://www.pivotaltracker.com/story/show/45628561

The current, default configs are wrapped up in the WEB-INF and are not particularly friendly to deal with. Do we need a fedora.home variable to go hunting for configs? 

We know this is done when, as a repository administrator (of the demo repository, at least), I can configure where the fcrepo data is persisted (aka outside of the ./target).