Remove codecov badge, add proper sized circleci

Author: pgrigoruta

README.md

@@ -2,9 +2,8 @@
 
 [![Packagist](https://img.shields.io/packagist/v/contentful/core.svg?style=for-the-badge)](https://packagist.org/packages/contentful/core)
 [![PHP from Packagist](https://img.shields.io/packagist/php-v/contentful/core.svg?style=for-the-badge)](https://packagist.org/packages/contentful/core)
-[![CircleCI](https://circleci.com/gh/contentful/contentful-core.php.svg?style=shield)](https://circleci.com/gh/contentful/contentful-core.php.svg?style=svg)
 [![Packagist](https://img.shields.io/github/license/contentful/contentful-core.php.svg?style=for-the-badge)](https://packagist.org/packages/contentful/core)
-[![Codecov](https://img.shields.io/codecov/c/github/contentful/contentful-core.php.svg?style=for-the-badge)](https://codecov.io/gh/contentful/contentful-core.php)
+<img height="28px" src="https://circleci.com/gh/contentful/contentful-core.php.svg?style=svg"/>
 
 ## What is Contentful?