Use an iframe to create a testDocument…
instead of `createHTMLDocument` since it isn't fully support by the browsers we care about.

fixes #606
fixes #454
remove warning comment about `createHTMLDocument`
IE support
jsx & JSDOM support
Remove unused event plugin registrationNamesKeys
Tweaks to README

Most significant change is updating the leading copy to match #440.
Merge pull request #625 from spicyj/patch-3

Tweaks to README
Add missing license header
Fix frontpage example to retain selection
Merge pull request #626 from spicyj/getUnboundedScrollPosition-license

Add missing license header
Merge pull request #609 from subtleGradient/subtlegradient/fixes-ios-crasher

fixes iOS crasher
Fix lint warnings
[docs] Fix download links to addons builds
Fix blog pagination

I missed this in the Jekyll upgrade.
Merge pull request #624 from spicyj/remove-registrationNamesKeys

Remove unused event plugin registrationNamesKeys
Add video at the bottom of the front page
Space optimizations for ReactMount.findComponentRoot.
Address pull request feedback.
Remove unused updatePropertiesByID
Merge pull request #630 from spicyj/remove-updatePropertiesByID

Remove unused updatePropertiesByID