Create composer.json file to allow its usage via composer

composer.json

+{
+    "name": "bouncexperts/dddbl",
+    "type": "library",
+    "description": "DDDBL - Definition Driven Database-Layer",
+    "keywords": ["PHP","Database","PDO"],
+    "homepage": "https://www.dddbl.de",
+    "license": "MIT",
+    "authors": [
+        {
+            "name": "Torsten Zuehlsdorff"
+        }
+    ]
+}