Recompose: Observable Config for RxjsV6.x

[isubasti]

rxjs have just released v6.x and rxjsObservableConfig does not work since they introduce some breaking changes. refer to migration guide to support rxjs V6.x

[wuct]

I've created a PR for it.

[shroomist]

we need this!

[elmarburke]

I would also love to use RxJS v6. Maybe you can share the blocking parts you see or where help is needed.

Is the change done in #660 a starting point or need more parts to change for v6?

Is moving to create-subscription really needed to make it work (now)? This will lead to a BC with at least react@^16.3.0