Reconnect app and underlying library

[rufuspollock]

demo/lib.js is diverging from underlying node library (in fact we do not directly use the underlying library). This is leading to bugs and duplication (e.g. underlying library adds description to generated schema fields but app does not).

We should reconnect these by having the app depend more on functions in the library (and updating library to support this).

This is also an opportunity to work more on #2.

[rufuspollock]

Open question whether we keep demo at all or just focus on https://github.com/frictionlessdata/datapackagist

May be some value in having the demo as super simple ...