Various belated content updates
Content:
- Added Michael Hales' Mayflower to homepage slideshow.
- Added Keith Pegram's Mayflower to homepage slideshow.
- Added Ralph Stephan's car wanted advert.
- Removed Dorien's "grille wanted" advert.
- Removed outdated cars for sale adverts.
Refactors:
- Git-ignored Jekyll's new auto-generated cache directory.