Administrator should be able to access and restore deleted attachments

Recently a user erroneously deleted a group of attachments from a page, but was not supposed to have that level of access. In order to fix the error, the admin had to figure out the identity of and find original versions of the attachments.

A 'restore deleted attachments' should be an option for a designated period of time after attachments are removed. There should be a global recylcing bin, for example.