Pin zc.buildout (not sure whether this works, though).
Add single real test to start with preparing Travis CI.
Define requirements for testing.
Use test-dependencies of devel package when running tests.
Use Plone 4.2.5 as base.
Pin more package versions. These new ones will be needed with Travis CI.
Add a buildout config for running tests with travis CI. As described
on http://datakurre.pandala.org/2012/09/speed-up-your-plone-add-on-tests-on.html