Added support for reCaptcha Mailhide addresses in static pages

Changed width of pages to 960px, from 1280px, to increase support
across devices.
Added contact details to Items#index and Items#show views.
Changed static pages to process <email> tags into Mailhide links
Added reCaptcha keys to application.yml.
Added email_safe method to String class, which converts <email> tags
into mailhide links
Added RecaptchaMailhide Gem