Upgrade to React 16

[nickytonline]

React 16 has been released, so we need to look into upgrading it in the project. Maybe it's a simple upgrade, maybe not ;).

@coryhouse, since this is used for your courses on Pluralsight, are you OK with us doing an upgrade to React 16?

[coryhouse]

This isn't tied to my courses, so we're free to upgrade. That said, the ecosystem will need a few days to update their dependencies to accept React 16, so a bit early. But yes, let's upgrade soon.

[kwelch]

I will take this, I planned on doing some package upgrades tonight as it is.

[kwelch]

Had to do more than just packages (I think we expected that). There are also some prettier format changes in their. The prettier updates I am sorry for, the rest I feel really good about 😄

[kwelch]

Closed in #480