Piper/add travis based testing

### What is the problem / feature ?

This package appears to have a nice test suite, but it is not being run automatically.  This can make it hard to evaluate the current state of the project (are all the tests passing?), as well as hard to know if a pull request is potentially breaking something without pulling the branch down and running the tests yourself.

### How did it get fixed / implemented ?

- Add a `.travis.yml` file to run all of the tests declared in the `tox.ini` file as well as the travis badge to the readme to indicate whether the tests are passing or not.
- In order for this to work in the main repository, one of the contributors to this project will need to go enable travis.  http://docs.travis-ci.com/user/getting-started/

### How can someone test / see it ?

See that this pull request is marked as *safe to merge* since all the tests pass (hopefull)

*Here is a cute animal picture for your troubles...*

![cute-squirrel-l](https://cloud.githubusercontent.com/assets/824194/4595284/d9dfac3a-5097-11e4-9cf1-a8a0804bc8f6.jpg)