Added page copy action to admin
Use custom user model in tests
Merge branch 'master' into page-copy-ui

Conflicts:
	wagtail/wagtailadmin/views/pages.py
Merge branch 'master' into test-with-custom-user-model

Conflicts:
	wagtail/tests/models.py
	wagtail/tests/utils.py
	wagtail/wagtailcore/tests/test_page_permissions.py
	wagtail/wagtaildocs/tests.py
Add usage counters for images, documents and snippets
Merge branch 'master' into 146-display-calculated-usage

Conflicts:
	wagtail/wagtaildocs/models.py
	wagtail/wagtailimages/models.py
Merge branch 'master' into 146-display-calculated-usage
Pull all test database options from env variables

Just pulling two and assuming others broke the base configuration I was
using, which uses a different database name and has a password.
Add document usage count tests
'Usage' page now displays a table of pages. Add new 'USAGE_COUNT' setting.
Add unit tests for usage feature
Merge branch 'master' into 146-display-calculated-usage
Remove stray print statement
Change assertRegexMatches to assertRegex
Set owner of copied pages to the user who copied them
Alter wagtailadmin.utils.used_by()

wagtailadmin.utils.used_by() no longer assumes that model
relationships to pages are named 'page'. Instead it assumes that all
ParentalKey relationships are relationships to pages.
Added option to copy form to publish copied pages. This is not displayed to users without publish permissions.
Merge remote-tracking branch 'torchbox/master' into page-copy-ui

Conflicts:
	wagtail/wagtailadmin/forms.py
Improve 'used by/usage count' implementation

- used_by() generates a database query instead of looping over a list of
  objects.
- usage_count() removed. Call count() on the queryset returned by
  used_by()
- Changed USAGE_COUNT to WAGTAIL_USAGE_COUNT_ENABLED. Added an inclusion
  tag for it.
Fix unit test failures