Travis CI

Integration of the [Travis](https://travis-ci.org/) Continuous Integration server.This script will build ArduCopter, Plane and Rover for the apm and px4-v2 builds.

Travis-CI has a good integration with GitHub. You just need to open the settings at https://travis-ci.org/profile/diydrones and enable the Travis Integration with GitHub. An example of this integration can be seen at https://github.com/arthurbenemann/ardupilot/pull/2

This PR depends on https://github.com/diydrones/ardupilot/pull/1192 being merged.