[FEATURE] Add Composer file

Introduce Composer to the project.

Refs matomo-org#48

.gitignore

@@ -2,4 +2,5 @@
 /tests/vendor/
 /.vagrant/
 /config.php
-/.idea/
+/.idea/
+/vendor/

composer.json

@@ -0,0 +1,20 @@
+{
+    "name": "matomo/tracker-proxy",
+    "description": "HTTP proxy for Matomo's tracker API. This script allows to track websites with Matomo without revealing to your visitors the secret Matomo server URL.",
+    "type": "project",
+    "license": "GPL-3.0+",
+    "authors": [
+        {
+            "name": "The Matomo Team",
+            "email": "[email protected]",
+            "homepage": "https://matomo.org/team/"
+        }
+    ],
+    "require": {
+    },
+    "require-dev": {
+    },
+    "config": {
+        "sort-packages": true
+    }
+}