Test more platforms

[sqeezy]

At the moment only windows and Linux is tested. It would be good to at least have OSX im addition. Maybe even different Linux flavors.

[jmschuaquico]

I'm using this in Unity3D, I could probably post whether it compiles on other platforms (OSX, iOS, Android) later.

[sqeezy]

I think we can just do that with travis.ci
I'm not sure whether linux platforms diversity is important, as this is a pretty hardware independent library.