Feature/smarter paths

Uses a handy module, [npm-path](/timoxley/npm-path), for constructing an `npm run-script` like PATH for use in the deployed applications' environment.

The second commit goes a step further and adds the deploy application's dependencies path to the PATH. This may or may not be desired.

@sam-github any suggestions on the easiest way to test this in various scenarios? Publish to the staging registry?