indicated deleted categories clearly on the body admin

this has been catching me out for years :-)
add toggle button to hide contacts, closes #505
remove SHOW_ADMIN_HINTS config

admin hints are displayed *like it or not*
(actually, could hide for a given cobrand with CSS setting display:none)
move override/devolved checkbox outside of hidden/revealed div

This checkbox should not only be revealed if the send method is not email, because it potentially applies all the time
bring back "devolved" to describe contact-specific endpoints

I thought the word "override" was clearer, but I was wrong
add "no results" message on user search
add "no reports found" message to reports search
jslint fixes