invalidate cache on page move

Signed-off-by: Martin Koistinen <mkoistinen@gmail.com>
Invalidate page cache on change of in_navigation by way of a new method on the Page model

Signed-off-by: Martin Koistinen <mkoistinen@gmail.com>
Invalidate the cms page cache on page publish

Signed-off-by: Martin Koistinen <mkoistinen@gmail.com>
Invalidate cms page cache on change to page.application_urls

Signed-off-by: Martin Koistinen <mkoistinen@gmail.com>