Added YAML parser node (#1034)

Thanks @natcl -
(sorry pressed closed by mistake !)
* Added YAML parser node

* Added YAML error strings in messages.json

* Change location of YAML library import

* Remove copyright

* Remove copyright

* Change order of yaml in Template node

* Add YAML test

* Add working test

nodes/core/locales/en-US/messages.json

@@ -614,6 +614,13 @@
             "dropped-error": "Failed to convert payload"
         }
     },
+    "yaml": {
+        "errors": {
+            "dropped-object": "Ignored non-object payload",
+            "dropped": "Ignored unsupported payload type",
+            "dropped-error": "Failed to convert payload"
+        }
+    },
     "xml": {
         "label": {
             "represent": "Represent XML tag attributes as a property named",