Enable local/appwide editable default local LiquiDoc settings

[briandominick]

LiquiDoc has some default assumptions, mostly in line with the LiquiDoc CMF framework, for lack of a better model. We should be able to reduce command-line even more by letting people set all kinds of defaults in a dotfile or something. So I'm thinking .liquidoc.yml, just to list your preferred local default config settings per-app.

We could also allow users to have personal (local, systemwide) defaults. This may require adding LiquiDoc to the PATH or something -- I really need to look into this.