Add continuous integration

[vmx]

This repository really needs proper continuous integration. The tests should be run before every commit (possible also the node binding test suite).

[atd-schubert]

Maybe I can help you with that...

Is the travis-ci a good choice for you?

[vmx]

Sure, Travis is fine. Whatever works :)

[atd-schubert]

@vmx FYI: You have to activate this repo on https://travis-ci.org/. Otherwise the CI will not work...

[vmx]

@atd-schubert Thanks for the information, it looks like it works now (#57).