Add about and corporate links to executive orgs

Brought the organisation description back onto the executive office
pages.

Moved the corporate information links up to next to the description.

Added the 'promo' and 'feature' classes back to the promo and features
as we should avoid using underscores in our classes where ever possible.
(Do as the language does).
Merge pull request #466 from alphagov/exec-description

Add about and corporate links to executive orgs

https://www.pivotaltracker.com/story/show/48123295