Export configure

I was upgrading a script which calls docco from 0.4.0 to the current version, and ran into an issue where I couldn't set any options (without running everything through commander) as `configure` is not exported.

Let me know if you'd rather I rework it so that sources can be passed into configure as `options.sources`, rather than `options.args`. (e.g. moving the args => sources transform into `run`).