[WIP] Add PHPCS and PHPCov

[petrabarus]

Just a bit help on setting up the PHPCS and PHPCov.

TODO:

• Choose appropriate coding guideline
• Add xdebug in http://github.com/tanibox/php7-fpm-nginx-supervisord/ for coverage support
• Integrate with codecov/coveralls.

[bepitulaz]

Thanks, @petrabarus. Just tell when it's finished.

[petrabarus]

@bepitulaz @lynxluna you guys use this for test/dev or prod?
https://github.com/Tanibox/docker-php7

[lynxluna]

@petrabarus it's for production environment, but we're currently re-use them also for dev.

I saw that you want to put xdebug to the image. I'd prefer to use different image augmented from the production image. You can PR to the repo, and I'll take care the hub registration.