Using pool in options object
Hey there, 

I have a question regarding the pool option. I'm catching this promise rejection 
`{ error: 'invalid_site_key' }` whenever I put in a `pool` with the subsequent properties. I know that the site key I'm using is valid because if I remove the `options` object in general it works. 

My question is, is this a cryptic error that is potentially something else? I've been using the default pool provided in the example. 