use the osx_defaults module instead of osx.sh

[mwilliammyers]

Ref. tasks/main.yml:15

# TODO: use the osx_defaults module instead of osx.sh
- name: OS X | configure
  shell: osx.sh
  when: ansible_distribution == 'MacOSX'
  tags:
    - bootstrap
…

[mwilliammyers]

Also verify correct syntax for El Capitan