Added npm lock files

[tyearke]

Description

This pull request adds the lock files generated by npm v5 to this repo. This will lock down the npm dependencies in a manner similar to how Composer locks dependencies.

It also updates a Travis setup script to ensure npm is up to date.

If approved, similar pull requests will be opened for other XDMoD repos.

Motivation and Context

npm v5 automatically generates package-lock.json files similar to how Composer generates composer.lock files. Like the latter's lock files, they are designed to ensure that consistent environments are generated across instances and are intended to be checked into source control.

Tests Performed

I verified that tools pulled in by npm continue to work, and I verified that the changes to the Travis script work as intended.

Checklist:

• My code follows the code style of this project as found in the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.