don't fall when busy

[tttp]

@sandramchung I finally found the library I was mentioning at the summit
I don't know where you had speed issues, but adding a test:

if (toobusy()) 
{ return randomly one of the variant instead of going all bayes and stats)
}  
bandit.choose

https://www.npmjs.com/package/toobusy-js

This one is for later, because I don't expect to have speed problems for a while

[schuyler1d]

I'd rather implement caching so that we're not too busy :-) (see #30 ). At least our instance is rarely blocked by cpu -- it's mostly the db.

[sandramchung]

We meant to address this in our last ops spike, but got cut short by an urgent project. It's the next major piece I'm working on.