support glob path expansion with a `lineman config --expand` flag

[davemo]

I'd like to be able to have a flag, something like lineman config --expand which would both interpolate the underscore <%= files.webfonts.vendor %> and also expand the glob path to get the list of matched files so I can see them using the nice keypath navigation of lineman config.

Right now the only way to sort of achieve this is with lineman run -v :P

[malcolmalex]

I'd +1 that.

[davemo]

As per @jasonkarns recommendation going to rename this to --expand