Add React docset

https://github.com/facebook/react/issues/272

This satisfies the docset contribution checklist I believe.
Merge pull request #123 from chenglou/react

Add React docset
Processed docsets/React/React.tgz
Processed docsets/React/versions/0.11.1/React.tgz
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Merge pull request #124 from neoneo/master

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