Enable travis tests for Plone 4.0 and Plone 4.1
Always require p.a.testing >= 4.2.2
travis updates

- Use consistent python naming
- Remove creation of eggs directory, it should exist after unpacking buildout-cache.
- Be quiet during buildout
- Enable timeout for buildout
Pin version of plone.app.testing in Plone 4.1 and Plone 4.0 buildouts
Pin p.a.testing in travis to succeed tests in Plone 4.1 and Plone 4.0
Documentation updates