9.0 release post

Preview https://release-9-0.about.gitlab.com/2017/03/22/gitlab-9-0-released/

This MR includes the new look of release posts. Any doubts, concerns? Please ask @marcia or @dimitrieh :)

Todos:

• Intro
• MVP
• Upgrade barometer
• Main features (missing)
• Check docs (Axil)
• Webcast link (Erica)
• Mention meetups and link to events page (Marcia)
• Copyedit (Sean P., 20th)
• Fix badges. They are not correct per features. And they are not on all features.
• Styling fixes (Dimitrie, 17th-20th)
• Last structural check (Marcia, 21st)
  • Compress cover image
  • EE/CE badges consistency (h2/h3)
  • Search for broken links
  • Meaningful links
  • Check end of divs (if they weren't deleted by mistake)
  • Check <!-- more --> separator
  • Check <hr> before cover image reference
  • Remove the instructions section
  • Remove html comments
  • Update template with last changes

Review app specific link: https://release-9-0.about.gitlab.com/2017/03/22/gitlab-9-0-released/