add composer configuration

composer.json

@@ -0,0 +1,41 @@
+{
+    "name": "menrath/wordpress-activitypub-event-extensions",
+    "description": "The ActivityPub Event Extensions help for event custom post types to federate properly.",
+    "type": "wordpress-plugin",
+    "require": {
+        "php": ">=5.6.0",
+        "composer/installers": "^1.0 || ^2.0"
+    },
+    "require-dev": {
+        "phpcompatibility/php-compatibility": "*",
+        "phpcompatibility/phpcompatibility-wp": "*",
+        "squizlabs/php_codesniffer": "3.*",
+        "wp-coding-standards/wpcs": "dev-develop",
+        "dealerdirect/phpcodesniffer-composer-installer": "^1.0.0",
+        "sirbrillig/phpcs-variable-analysis": "^2.11"
+    },
+    "config": {
+        "allow-plugins": true
+    },
+    "allow-plugins": {
+        "composer/installers": true
+    },
+    "license": "AGPL",
+    "authors": [
+        {
+            "name": "André Menrath",
+            "email": "andre.menrath@event-federation.eu"
+        }
+    ],
+    "extra": {
+        "installer-name": "activitypub-event-extensions"
+    },
+    "scripts": {
+        "lint": [
+            "vendor/bin/phpcs -n -q"
+        ],
+        "lint:fix": [
+            "vendor/bin/phpcbf"
+        ]
+    }
+}