Add support for testing the project on Travis-CI

I'm working on a pull request that will bring postgres support to the project, but first I wanted to see up-to-date informations about the project test suite.

I've managed to get green tests on [Travis](https://travis-ci.org/trekdemo/jobsworth) with `mysql` and mri 1.9.2 & 1.9.3.

Please let me know if this RP needs some other changes!