Update Google config docs

[hbillings]

Screens have changed pretty significantly since our screenshots, especially the client ID creation.

[hbillings]

Actually, there's now a screen that asks for a "redirect URI." Leaving it blank (or even putting localhost in) results in not being able to authenticate client_secrets.

[eads]

hmmm, you should be making an installed app which doesn't require a redirect

[hbillings]

Oh good lord. I need more coffee.

[rnagle]

[hbillings]

So Google has updated their dev console again, and none of the old screenshots match it. Wheeee.