FIX Fixes #965. Allow user date-settings to show on GridField Page admin

- Relies on framework PR #2961.
BUG Fix orphaned pages reporting they can be viewed
Merge pull request #991 from tractorcow/pulls/3.1-canview-orphaned

BUG Fix orphaned pages reporting they can be viewed
Merge pull request #968 from phptek/issue/965

FIX Fixes #965. Allow user date-settings to show on GridField Page admin
Merge remote-tracking branch 'origin/3.1'