Fix 'Host key verification failed.' errors by using this cap task

deploy.rb

# Add this to your capfile if you're getting burned on first deploy to a new host
# If you're getting 'Host key verification failed.' errors on your initial
# checkout of a repo using capistrano, this will fix it up

task :a_friend_of_mine_is_a_friend_of_yours do
  # transfer what *I* know about github to the host
  github_known_hosts_line = `cat ~/.ssh/known_hosts | grep github.com`
  run "echo #{github_known_hosts_line} >> ~/.ssh/known_hosts"
end