Update README.md
flip ahead should use prev, not previous as rel.
Fixed link rel;for previous, which is now prev.
fixing demo page 1: prev link rel
fixing demo page 2: prev link rel
fixing demo page 3: prev link rel
Fixed link rel;for previous, which is now prev. properly this time.
add drone.io badge to readme
Merge pull request #1 from AVGP/master

Fixed rel name for previous content link to match IE convention.