Use Tres' handy upgradeException function, to make the ExceptionHookTest work across Python versions

Updated all packages to latest maintenance releases. Also updated ZConfig and pytz to latest features release.

Added support to indexing datetime values to the PluginIndexes DateRangeIndex. The DateIndex already had this feature.

Removed handling of string exceptions from ZPublisherExceptionHook and reverted the addition of Unauthorized exceptions to be always re-raised. This broke the tests.

  with "bin/zopectl adduser"

- removed special PluginIndexes handling in Product initialization code

- added more XXX comments to the regression tests (don't know how to run and fix them)

- added XXX comments to the regression tests (don't know how to run and fix them)

o Added tests for previously-untested clients.

o Uupdate versions for new location:

  - zope.pagetemplate==3.5.0
  - zope.app.pagetemplate==3.7.0
  - zope.app.publisher==3.8.1