Nodes that have had their child removed already, but then get given a new one no longer bug-out.

In the case of having an animated node which is, after the leave-transition has been activated, then re-added in a render call causes React to 'break'.  This is especially noticeable if you spam to removal and re-addition of an item in a ReactTransitionGroup.

This fix simply stops the leave transition and restarts the enter transition.
Updated the animation-fix to account for transitionEnter being false.
Fix scrollLeft/scrollTop warning in latest Chrome

Chrome gives the warnings

```
body.scrollLeft is deprecated in strict mode. Please use 'documentElement.scrollLeft' if in strict mode and 'body.scrollLeft' only if in quirks mode.
body.scrollTop is deprecated in strict mode. Please use 'documentElement.scrollTop' if in strict mode and 'body.scrollTop' only if in quirks mode.
```

the first time getUnboundedScrollPosition is invoked. This fixes it. (All modern browsers support `pageYOffset`; IE 8 doesn't but works properly with `document.documentElement.scrollTop` except in quirks mode which React doesn't support.)
Community Round-up #14
Fix "Dynamic Children" example
Merge pull request #642 from Cartas/master

ReactTransitionGroup can handle components being re-added before 'leave' transition has completed.
Note about react's version on the talk, since somethings have already changed since then
Removed unnecessary cleanup in isEventSupported
Adding note about onScroll on IE8
updating text as suggested by @petehunt
language update as suggested by @petehunt
Merge pull request #703 from fabiomcosta/onscroll-doc-ie8-note

Adding note about onScroll on IE8
Merge pull request #701 from fabiomcosta/react-video-version-note

Note about react's version on the video talk
Merge pull request #702 from syranide/lessmice

Removed unnecessary cleanup in isEventSupported
Add a talks section to the docs
Merge pull request #704 from vjeux/talks_doc

Add a talks section to the docs
docs remove video at the bottom
Merge pull request #705 from chenglou/rm-vid

docs remove video at the bottom
Update README.md
transferPropsTo should never transfer the key property