Add configuration file for travis CI

This pull request is more an *experiment* than an actual improvement to your software.

I was just playing arround with https://travis-ci.org and I made this configuration file just for fun' (build results could be found here: https://travis-ci.org/riton/heimdal)
If you're interested, feel free to take it and adapt. If not, just close the pull request.

Cheers