Add plone 4.3 tests buildout.
No longer pin down Products.PloneFormGen: 1.6 is not compatible with 4.3.
Use zope.lifecycleevent interfaces for Plone 4.3 compatibility.
Add Plone 4.3 compatibility changelog entry.
Merge pull request #3 from 4teamwork/jone-plone-4.3

Plone 4.3