Ansible 2.6 Testing Support

[danquack]

Changes:

• Updated default travis config to use Ansible 2.6.1
• Added Ansible 2.6 and 2.6.1 to validation
• Sectioned out with comments distribution and python versions in travis config
• Added commented build status for future use in readme
• Updated ansible.rst to include updated links for Ansible 2.6

Issues Resolved:
closes #311

[dw]

This is great, thanks a ton! The travis badge is intentionally not in the readme at present due to those flakey tests, but i can merge as-is and delete that later. Thanks again!

[danquack]

@dw commented out the badge to make your life a little easier.

[dw]

Thanks a million!