Automatically create a pip requirements file based on the prod versions.

Currently there are a small number of test failures and errors.

I was too quick to remove it.

Copy more of the zope.testbrowser.testing code, as it got moved
into zope.app.testing and we want to avoid a dependency on any
zope.app package.

This is no longer a persistent object.

Apply hotfix 20160419 [master]

Needed by Products.five.

It imports ObjectEvent from zope.interface.interfaces which was moved there in 3.8

Optimize "OFS.ObjectManager.__contains__" method

From Products.PloneHotfix20160419.

use newer versions of everything (except zope.testbrowser)