Add Node.js test suite

[asbjornu]

As surfaced in #1402 (comment), the TFS Task related stuff uses Node.js, which means we currently have no continuous integration setup with tests for much of the TFS related code. This is a problem and we need to create a Node.js based test suite that can be executed with npm test on our continuous integration infrastructure.

[stale]

This issue has been automatically marked as stale because it has not had recent activity. After 30 days from now, it will be closed if no further activity occurs. Thank you for your contributions.