Attach a uid to all errors

[patcon]

Thinking on debugging this made me realize this would be useful:
#2372

Showing a uid and logged it would make it much simpler to help see the context when troubleshooting. Our audience tends to be fairly technical, so I think most would know to pass along the crazy-looking alphanumeric error id :)

[chadwhitacre]

You mean a unique id or a user id?

[Changaco]

Closing in favor of #2441.