Add ES6 / Babel / Flow / Relay content

[alexlupu]

I understand it's hard to keep up with all of these changing technologies, but I and other learners would greatly appreciate updating your talk with these new features / frameworks, even if it just starts with one or two dedicated slides at the end for each topic and then references for later.

[fkling]

We are actually planning to create separate presentations for them. But we can definitely at least reference them.