Update README and CHANGELOG

[skip ci]

Author: matthiasnoback

CHANGELOG.md

@@ -6,6 +6,7 @@
 - Only support Symfony 2.* and 3.* LTS versions
 - Require PHP ^7.0
 - Drop support for HHVM
+- Deprecated `Matthias\SymfonyConfigTest\PhpUnit\AbstractConfigurationTestCase`, use `Matthias\SymfonyConfigTest\PhpUnit\ConfigurationTestCaseTrait` instead.
 
 ## 2.0.0
 

README.md

@@ -16,8 +16,6 @@ Using Composer:
 
 ## Usage
 
-### PHP 5.4 and up
-
 Create a test case and use the trait from ``Matthias\SymfonyConfigTest\PhpUnit\ConfigurationTestCaseTrait``.
 Then implement ``getConfiguration()``:
 
@@ -35,23 +33,6 @@ class ConfigurationTest extends \PHPUnit_Framework_TestCase
 }
 ```
 
-### PHP 5.3
-
-Create a test case and extend from ``Matthias\SymfonyConfigTest\PhpUnit\AbstractConfigurationTestCase``. Then implement
-``getConfiguration()``:
-
-```php
-<?php
-
-class ConfigurationTest extends AbstractConfigurationTestCase
-{
-    protected function getConfiguration()
-    {
-        return new Configuration();
-    }
-}
-```
-
 ### Test invalid configuration values
 
 Let's assume the ``Configuration`` class you want to test looks like this: