Update team titles and index ordering

- Louis Tatta: Executive Team → CFO/COO (index card,
  bio Chief Operating Officer → CFO/COO)
- Sam Darwin: Executive Team → CTO (index card,
  frontmatter shortened from Chief Technology Officer)
- Mark Cooper: Consultant → CMO (index, frontmatter)
- Rob Beeston: Creative Director → Chief of Staff
  (index, frontmatter, bio); card moved after Mark
- Krystian Stasiowski: moved from alumni back to the
  active team (layout + index card relocation)

Author: CircleCI