Add changelog, contributing and deps configuration

Author: timoschinkel

CHANGELOG.md

@@ -0,0 +1,15 @@
+# Changelog
+All notable changes to this project will be documented in this file.
+
+The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
+and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
+
+## Unreleased
+Initial set up.
+
+### Added
+- Initial version of code, including unit tests
+- README
+- CHANGELOG
+- CONTRIBUTING.md
+- Composer configuration

CONTRIBUTING.md

@@ -0,0 +1,20 @@
+# Contributing
+
+When contributing to this repository, please first discuss the change you wish to make via issue,
+email, or any other method with the owners of this repository before making a change. 
+
+This repository is offered as open source and is maintained by volunteers. Please treat the contributors the way you 
+would like to be treated yourself.
+
+## Pull Request Process
+
+1. Ensure any install or build dependencies are removed before the end of the layer when doing a 
+   build.
+2. Ensure the code follows coding style and is tested. If a CI pipeline is set up ensure the Pull Request passes the CI 
+   pipeline.The coding standard we use is [PSR-12](https://www.php-fig.org/psr/psr-12/).
+3. Update README.md and other applicable documentation within the repository to reflect the changes in the Pull Request.
+4. Update the CHANGELOG.md with a new version number and details of changes to the interface, this includes new environment 
+   variables, exposed ports, useful file locations and container parameters. The versioning scheme we use is 
+   [SemVer](http://semver.org/).
+5. You may merge the Pull Request in once you have the sign-off of by a code owner, or if you 
+   do not have permission to do that, you may request a code owner to merge it for you.

phpcs.xml

@@ -0,0 +1,11 @@
+<?xml version="1.0"?>
+<ruleset name="PHP_CodeSniffer">
+    <arg name="basepath" value="."/>
+    <arg name="colors"/>
+    <arg value="s"/>
+
+    <rule ref="PSR12" />
+
+    <file>src/</file>
+    <file>tests/</file>
+</ruleset>

phpunit.xml.dist

@@ -0,0 +1,21 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+        colors="true"
+        failOnRisky="true"
+        failOnWarning="true"
+        verbose="true"
+>
+    <testsuites>
+        <testsuite name="Http Client Middleware Test Suite">
+            <directory>./tests</directory>
+        </testsuite>
+    </testsuites>
+
+    <filter>
+        <whitelist>
+            <directory suffix=".php">src</directory>
+        </whitelist>
+    </filter>
+</phpunit>