pushing to heroku with travis

.travis.yml

language: ruby
rvm:
  - 1.9.3

#after_install: 
# I had to move all the steps into the after_script to get them called

after_script:
  - gem install heroku
  - export HEROKU_API_KEY=<your key here> # you probably want to encrypt this key using the travis gem and "travis encryp" cmd
  - yes | ruby travis_deployer.rb
  - heroku keys:clear
  - yes | heroku keys:add
  - git push heroku master # or whatever your heroku push looks like

travis_deployer.rb

File.open(".git/config", "a") do |f|
  f.puts <<-EOF
[remote "heroku"]
    url = url = git@heroku.com:your-app-here.git
    fetch = +refs/heads/*:refs/remotes/heroku/* # had to change this into remote name instead of app name
EOF
end

known_hosts = File.expand_path("~/.ssh/config")
File.open(known_hosts, "a") do |f|
  f.puts <<-EOF
Host heroku.com
   StrictHostKeyChecking no
   CheckHostIP no
   UserKnownHostsFile=/dev/null
EOF
end

Am having some issues with the user authentication with this. Travis build keep getting a prompt to enter the heroku credentials. how do I fix this?