Integrate continous integration with Travis CI

I had some fun integrating Travis CI to execute the test suite. I rather mercilessly hacked at the testing code, and sometimes also at the production code, but more likely on the actual configuration.

Travis CI offers a whole bunch of databases, but they come with a certain default configuration that made it necessary to change the credentials.

There are actually two steps involved to get the full benefit.

1. Obviously the pull request must be merged.
2. More important, someone with administrative power must enable Travis CI to have access to the OWASP repositories and enable execution for the tests for this phpsec project.

Benefits: The current setup executes the tests on PHP 5.3, 5.4 and 5.5, and tries to use MySQL, Postgres and SQLite3.

There still is work to do: Postgres tests don't run at all, many tests echo results to STDOUT without that being asserted, and some tests don't assert anything at all.