Provide ability to turn off "Request Access" functionality.

The feature announced here;
https://blogs.atlassian.com/2013/09/new-in-confluence-request-access-to-view-restricted-pages/
Which is the implementation of;
https://jira.atlassian.com/browse/CONF-28346

...means that a user can request access to a restricted page in Confluence. This has the potential to generate a great deal of spam to page owners, as people request access to pages to which they should not have access.

We have restrictions in place for a reason. So we don't want people requesting access to pages to which they do not have access. We require the ability to switch off the "Request access" feature.

With this feature switched off, should a user attempt to access a page to which they do not have access, they should simply be told that they do not have access. They should not be given the option to request it, or even to see who the owner of the page is.

Ideally it would be possible to enable/disable the "Request Access" feature on a per-page (including child pages) basis, as well as per-space, and system wide.