Continuous integration on PHP 5.2

We need to run tests for Ascraeus on the minimum required configuration, which is presently php 5.2. phpunit 3.5 which is currently required requires 5.2.7.

This ticket, which I marked blocker for 3.1, is for setting up a CI environment (bamboo) which will be guaranteed to use php 5.2.

We should probably have one for 5.3 also, but 5.2 is the more important one.