Give bad link report email a body

Without explicit body text set, Amazon SES complains with a 554 error.
Increase logging around bad link reporting
Exclude CIPs from Latest box on Organisation page.
Merge pull request #1500 from alphagov/bad-link-reporting-tweak

Give bad link report email a body
Merge pull request #1501 from alphagov/exclude-cips-from-latest

Exclude CIPs from Latest box on Organisation page.
Fix null body fields on new About Us CIPs.
Do not require body on CIP about pages

The "about us" information was extracted out of the "description" and
"about_us" attributes on the Organisation model and turned into a new
CorporateInformationPage type of AboutUs, setting the "summary" and
"body" respectively. Because only "description" was required on
Organisation, there are now a number of CIP AboutUs pages that do not
have a "body" and are thus invalid. This change makes an AboutUs page
valid without a body, which means editors will not be forced to supply
an AboutUs body for organisations that do not need one (e.g. closed or
except organisations)
Merge pull request #1502 from alphagov/about-pages-without-body

CorporateInformationPage of type AboutUs do not need a body
Bump slimmer

This will give us more information in exceptions raised by slimmer
processors
Merge pull request #1503 from alphagov/bump-slimmer

Bump slimmer
Offsite links
New UI for featuring and unfeaturing items for topics, topical events, organisations and world locations.
Added the ability to feature offsite links on topics, topical events, organisations and world locations

https://www.pivotaltracker.com/story/show/66668192
https://www.pivotaltracker.com/story/show/70537384
https://www.pivotaltracker.com/story/show/70741400
https://www.pivotaltracker.com/story/show/70537546
https://www.pivotaltracker.com/story/show/70537432