add npmDependency and npmDevDependency specifications

Signed-off-by: Jason Van Pelt <jvanpelt@newrelic.com>

@davidcelis

I'm not sure how I feel about this. In the case of Ruby gems, we treat gems the same regardless of group, though technically we could ignore gems in the `development` and `deployment` groups. The same goes for NPM packages. Part of me feels like we should treat all of these package types the same, and validate licenses for everything including development dependencies.

However, another part of me feels like we should start ignoring dependencies that are not actually packaged with the app on deployment, such as NPM's development dependencies or the Gemfile groups I mentioned above.

If the dependencies aren't packaged up with the app, deployed, and distributed, we shouldn't care about their licenses. Darin (understandably) is very strict about this, but this is also now a public project that extends past us.

I think for now I'd rather just not split these. Let's keep it standardized and just validate everything. But if others come in and start asking about validating development dependencies, then I think this is a conversation we should have!