Error handling - Githubissues

this patch is mostly around handling user errors what were encountered in the first week of launch. namely:

more descriptive errors when credentials or params are incorrect
better server-side recovery functions when "log" sheets or "source" sheets get deleted
MUCH better analytics tracking and logging strategies
tests for all the things that users "did wrong"
removing "sync" functionality for events, because this requires further research

mixpanel / sheets