Added vulcanize under third_party/npm_modules

node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/index.js

Index: node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/index.js
diff --git a/node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/index.js b/node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/index.js
new file mode 100644
index 0000000000000000000000000000000000000000..92c9c9700aac7df57b1a3a7b8d23191d81d51a83
--- /dev/null
+++ b/node_modules/vulcanize/node_modules/update-notifier/node_modules/semver-diff/index.js
@@ -0,0 +1,27 @@
+'use strict';
+var semver = require('semver');
+
+module.exports = function (a, b) {
+	if (semver.gt(a, b)) {
+		return null;
+	}
+
+	a = semver.parse(a);
+	b = semver.parse(b);
+
+	for (var key in a) {
+		if (key === 'major' || key === 'minor' || key === 'patch') {
+			if (a[key] !== b[key]) {
+				return key;
+			}
+		}
+
+		if (key === 'prerelease' || key === 'build') {
+			if (JSON.stringify(a[key]) !== JSON.stringify(b[key])) {
+				return key;
+			}
+		}
+	}
+
+	return null;
+};