Automatically adding page_ownerships from facebook API

[sic2]

this operation can be done when creating the page.

As of today, this can be easily done for groups. Just have graph.facebook.com/ID-GROUP/admins and check that user is in the list.

However, the same api is not available for pages. We could, however, get the list of pages a user is admin of. In that case we will have to request some permission from the user on login.