View tests should probably not use Zopeless layers

[Gavin Panella]

Several view tests in lp.registry.browser.tests.test_distroseries use
LaunchpadZopelessLayer. This seems to be the wrong thing to do because
PermissiveSecurityPolicy is used in these layers.

I think this situation has arisen because layers are confusing. It's
difficult to know what you're getting without reading a lot of
code. When choosing layers I have often taken an approach like "find
the layer with the shortest name that lets my tests pass", and I know
I'm not the only one! We need to make layers more understandable,
perhaps through more documentation (though I groan at that thought),
or by replacing layers with a more transparent system.

*ZopelessLayer also appears in these other browser tests:

lib/lp/registry/browser/tests/test_person_view.py
lib/lp/registry/browser/tests/test_distroseries.py
lib/lp/translations/browser/tests/test_translationgroup.py
lib/lp/translations/browser/tests/test_product_view.py
lib/lp/translations/browser/tests/test_translatablemessage_view.py
lib/lp/translations/browser/tests/test_translationlinksaggregator.py
lib/lp/translations/browser/tests/test_persontranslationview.py
lib/lp/translations/browser/tests/test_distroserieslanguage_views.py

(find lib/lp/*/browser/tests -name '*.py' -print0 |
   xargs -r0 fgrep ZopelessLayer -l)