Remove Date.now() cache buster for url ping

Date.now() doesn't seem to be supported in older versions of IE.  Including `Math.floor(Math.random() * 1000000);` instead to force a unique url.

Will not guarantee a unique url like Date.now() would, but will make it fairly improbable for duplicates while supporting older browsers.

Also, ignoring the node_modules directory in .gitignore.