Add automated testing support

[Travis](https://travis-ci.org) is a free service that can automatically run tests for you when you push commits to a Github repository. Adding support for it is very simple, you create a '.travis.yml' configuration file saying what language you're using and the test to run then just log in to Travis and tell it what repositories to test.

Tests are run within a Ubuntu VM that you are free to install your own dependencies into. Once tests have been run you can look at the [console output](https://travis-ci.org/ScottWales/cylc/jobs/20497301) to identify any problems.

Since it's integrated with Github it will also add annotations to pull requests to say if the branch passes tests (shows up as an image next to the commit ids). You can also add a tag on the README like [![Build Status](https://travis-ci.org/ScottWales/cylc.png)](https://travis-ci.org/ScottWales/cylc) to show if the latest build passed.