Fixed bug, forgot registering command to entry_points
Added roll_validator and applying it to page_post_view.
Added a LICENSE file
Fixed bug on posting pages.

When POSTing a page from a editing of some views to any another pages,
and then the posded pages has a instasce, it will be error.
(Deplication error of row on DB)

So now the page posting become no to be able to specifying the page title.