Set up travis-ci

this sets up a free continuous integration server travis-ci.  

also adds `.gitignore`

Travis-ci integrates with github, and will automatically run on all pull requests if it is set up.

Here is an [example test report](https://travis-ci.org/tingletech/xtf)

[travis docs](http://docs.travis-ci.com)

[`.travis.yml` validator](http://yaml.travis-ci.org)