Run tests on multiple node versions in travis

[sudo-suhas]

The tests can run in parallel and the module can be used with confidence on the tested node versions.

[asfktz]

Waited for you to put your hands of that file 😉

I'm new to CI, so feel free to change it however you believe is necessary.

[sudo-suhas]

Waited for you to put your hands of that file 😉

Ha ha.. too much.

Here is a sample .travis.yml file - https://github.com/sudo-suhas/elastic-builder/blob/master/.travis.yml

I dunno how good it is though.. I started working on open source recently too.
Couple of things we can do:

• Cache node_modules. This can improve build times
• Add rule to not test branches created by npm version or yarn version.

As of now you are not using greenkeeper or a hosted service for coverage. While greenkeeper might be overkill right now, I can highly recommend https://coveralls.io/.

Let's discuss here before I make the PR for travis config change.

[sudo-suhas]

Actually none of these changes are needed per se. The current one will serve the purpose just fine.

[asfktz]

Yeah, I guess time will tell us what we need (: