Allow all roles to be translated

Previously we were restricting it to only worldwide roles.
Translate people#show and roles#show

Replaces all hard-coded text with translatable keys.
Regenerate locales with new keys for people/roles
Correct tests in light of translation changes
Merge pull request #820 from alphagov/46990889-translatable-roles

Translate user roles, linking to them as appropriate on the front end

https://www.pivotaltracker.com/story/show/46990889