Updated page_url doc

It was missing some arguments
Fix divio/django-cms#3575
remove unused import and commented out line
Merge pull request #3577 from benjaoming/fix_get_models_patch

Fix get models patch
Fixes #3575
relax url regexes to allow frontend editing of models with non numeric pks
Extract regexp for slugs as a reusable constant
Reuse SLUG_REGEXP in FrontendEditableAdminMixin
Add test for FrontendEditableAdminMixin.edit_fields url matches
Merge pull request #3574 from yakky/feature/doc_ychouinard

Updated page_url doc
Add supported_apps attribute to toolbar
Add tests for supported_apps
Add documentation for supported_apps
Fix typos
Improve supported_apps documentation
Small docs fixes
Merge pull request #3594 from evildmp/docs-quickfix

Small docs fixes
Add placeholder and view to CharPksExample
Move FrontendEditableAdminMixinTest to cms.tests.toolbar. Add View tests.
Rename FrontendEditableAdminMixinTest to CharPkFrontendPlaceholderAdminTest
fix tests, migrations