"Demo mode" for Contact Otter

[xet7]

Moved to here from phildini#35

From @phildini

I kind of want a "try before you buy" mode for ContactOtter.

In my vision, this would be a demo account that would populate itself with contacts, allow anyone to "login" to the demo account, play around, and then the account clears itself out every hour. (IIRC, the discourse site does this really well).

(@paulproteus, I expect, is going to say "What an amazing use case for sandstorm!", and there's a lot of truth to that, with one caveat: right now, I could start "selling" ContactOtter with ~1 day of stripe setup, and I could have demo mode lead right into a sale nicely. So long as I don't have the ability to sell on Sandstorm, my motivation to have people try out my app on sandstorm is lower, since I can't really redirect them back to my hosted app to "buy" it. Sandstorm wants to sell sandstorm, I want to sell my app, we are at a bit of an impasse at the moment.)

Basic implementation: Cron job that clears out the "demo" user and re-creates it every hour on the hour.