Update package.json

add Olivier as contributor

io/stomp/package.json

@@ -21,5 +21,8 @@
         "name": "Dave Conway-Jones",
         "email": "dceejay@gmail.com",
         "url": "http://nodered.org"
-    }
+    },
+    "contributors": [
+        "Olivier Verhaegen"
+    ]
 }