RequestController#search_typeahead filter by body

Action now supports the `request_from` param as per the Xapian filtering
system to filter search typeaheads by public body
Filter related requests by body on /new/:body
Refactor request/_search_ahead partial

Each instead of for
Unless instead of if !
.any? instead of size > 0
Line length
Only attempt to render results if there are any

No point trying to render the results if there aren’t any to render
Don’t render “search their website” if no results
Don’t render search ahead results if no results

Only render the request_search_ahead_results div when a search has been
made.
RequestController#search_typaahead limit results

Use the per_page parameter to limit the results returned
Limit typeahead similar requests on /new/:body

Only return 3 similar requests to prevent the suggestions swamping the
page
Add close button to similar requests on /new/:body
Add slideUp/slideDown to related requests results
Update CHANGELOG (Version 0.20)
Emphasise public body categories upgrade step
Add CensorRule factories
Specs for AdminCensorRuleController#new
Specs for AdminCensorRuleController#edit
Specs for AdminCensorRuleController#destroy

Note that these specs describe what the system does – not what it
_should_ do!
Use rack-utf8_sanitizer gem

This sanitises non utf-8 params before they're processed by Rails.
fixup! Use rack-utf8_sanitizer gem
Specs for AdminCensorRuleController#create

Note that these specs describe what the system does – not what it
_should_ do!
Specs for AdminCensorRuleController#update

Note that these specs describe what the system does – not what it
_should_ do!