adding a couple of npm scripts and tweaking travis

Added 2 new tasks:
1. `npm run lint-jsdoc` &mdash; Uses ESLint to check for valid/missing JSDoc comments. This only causes warnings if you run it locally and won't fail any builds.
2. `npm run audit-shrinkwrap` &mdash; Uses [**nsp**](https://github.com/nodesecurity/nsp) to check a npm-shrinkwrap.json file for any known vuln modules in the https://nodesecurity.io database. This script will create a npm-shrinkwrap.json file and uses `|| true` to make sure the exit code is always 0 so it won't fail the Travis build.

I also tweaked the .travis.yml file to log out any known questionable modules using `npm run audit-shrinkwrap`.