Styletron engine doesn't need to be initiated again if embedded app is using styletron already

[Firenze11]

Summary

In app where styletron is already used, the styletron engine within manifold component will conflict with the engine outside.

Current Behavior

E.g. if the app uses server side rendering, it will conflict with the engine within manifold which uses client side rendering

ReferenceError: document is not defined
    at new StyletronClient (/Users/agreco/dev/michelangelo-web-fresh/node_modules/styletron-engine-atomic/dist/index.js:660:7)
    at Object. (/Users/agreco/dev/michelangelo-web-fresh/node_modules/@mlvis/src/components/manifold.js:35:16)

Possible Solution

Remove styletron engine from within manifold; ask users to use styletron provider separately.