Added Travis CI config with Postgres and MySQL support

You'll need to sign in to travis-ci.org using your github credentials and authorize the web hooks to set up automatic building, but it's pretty self-explanatory. Also need to update the repo account name in the build badge on the first line of the README.textile, I couldn't figure out how to parameterize that... Also you'll need to adjust your local db names and passwords for compatability, if that's a deal-breaker I can set up a more complicated travis config to change out the credentials file when initializing the travis environment.