sudo apt-get update && sudo apt-get install -y python2.7 python-simplejson
ansible-galaxy install -r requirements.yml
e.g.
ansible-playbook site.yml -i production.inv --ask-pass --ask-become-pass -u [username] --ask-vault-pass
or
ansible-playbook site.yml -i production.inv --ask-become-pass -u [username] --private-key="~/.ssh/id_rsa" --ask-vault-pass