don't occupy subpages of Talk pages

Allows "See User_talk:Spage/Archive for what used to be on this page."
to work.
Also give examples of occupy globals.

Addresses an issue I found in
https://mingle.corp.wikimedia.org/projects/flow/cards/68

Currently you have to create a dummy normal wiki page before Flow can
take it over. I tried removing the test for page existence in
isTalkpageOccupied() and it didn't help. This method could dummy up a
page for you, but maybe we should rethink Flow's "Can only load
workflows for existing page."

Change-Id: I3a1f1e5617d3156177ec8b8724c518862dffa4a5
Merge "don't occupy subpages of Talk pages"