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/parsers/70-YAML.js

@@ -0,0 +1,34 @@
+module.exports = function(RED) {
+    "use strict";
+    var yaml = require('js-yaml');
+    function YAMLNode(n) {
+        RED.nodes.createNode(this,n);
+        var node = this;
+        this.on("input", function(msg) {
+            if (msg.hasOwnProperty("payload")) {
+                if (typeof msg.payload === "string") {
+                    try {
+                        msg.payload = yaml.load(msg.payload);
+                        node.send(msg);
+                    }
+                    catch(e) { node.error(e.message,msg); }
+                }
+                else if (typeof msg.payload === "object") {
+                    if (!Buffer.isBuffer(msg.payload)) {
+                        try {
+                            msg.payload = yaml.dump(msg.payload);
+                            node.send(msg);
+                        }
+                        catch(e) {
+                            node.error(RED._("yaml.errors.dropped-error"));
+                        }
+                    }
+                    else { node.warn(RED._("yaml.errors.dropped-object")); }
+                }
+                else { node.warn(RED._("yaml.errors.dropped")); }
+            }
+            else { node.send(msg); } // If no payload - just pass it on.
+        });
+    }
+    RED.nodes.registerType("yaml",YAMLNode);
+};