Configure Code Climate analysis and code coverage reporting

[simonengelhardt]

As suggested in #104

[simonengelhardt]

Repo has been imported: https://codeclimate.com/github/facebook/facebook-instant-articles-sdk-php

I will work with our admins to set up the update hook and configure code coverage.

[vincentkoc]

@simonengelhardt current travis build only supports PHPUnit tests. I have been working on a fork of a 3 year old CI toolset for wordpress plugins https://github.com/koconder/wordpress-test-template

This will allow for full testing beyond PHPUnit as it will load up a CI test using a Wordpress install. We can then test plugin against Wordpress versions and PHP version combinations as well as plugin co-dependency if any 3rd party plugins are integrated to see if anything breaks.

This would also help resolve any classes and function calls to WP and give better code coverage and code analysis. Thoughts?