Travis CI Integration

- pull in local copy of `shunit2`.
- test helper uses local `shunit2` by default.
- add a `.travis.yml` including `make test` for script value.
removed local `shunit2` per PR comments
revert helper.sh to use system `shunit` and travis.yml to install system `shunit2`
Merge pull request #157 from wilmoore/travis-ci

Travis CI Integration