Update debian.sh
Added page copy action to admin
Merge branch 'master' into page-copy-ui

Conflicts:
	wagtail/wagtailadmin/views/pages.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
Move/re-namespace existing users forms, templates, urls, views
Update users tests to match new namespacing
Add groups to wagtail admin interface
Add tests for wagtail admin group views
Add css for groups menu item
PEP-8
Customise permissions widget
Limit GroupForm permissions queryset to hook-registered permissions
Register permissions for images, docs, and registered snippets
Register 'access wagtail admin' permission
Split permissions table display into object permissions and other permissions
De-hardcode the button text in page_chooser_panel
Add page permissions formset to group edit view
Add inline chooser panel templates for group page permissions formset
Add uniqueness constraint on GroupPagePermission, and error tags in template