Make html2canvas requireable in nodejs

tests/node/package.js

@@ -0,0 +1,8 @@
+var assert = require('assert');
+var html2canvas = require('../../');
+
+describe("Package", function() {
+    it("should have html2canvas defined", function() {
+        assert.equal(typeof(html2canvas), "function");
+    });
+});