Moving React 0.11 into legacy

I'm following the example from Angular.
Renaming the legacy module for tests

Apparently they conflict otherwise which is unfortunate.
Renaming based on the new React API

http://facebook.github.io/react/blog/2014/10/16/react-v0.12-rc1.html#renamed-apis
Removing transferPropsTo
Adding the new Element types

https://gist.github.com/sebmarkbage/fcb1b6ab493b0c77d589
Fixing React Addons
Removed descriptors from our code
Fixing the version
Adding createFactory

Forgot about this piece but is important for removing warnings.
Fixing isValidClass and isValidElement

The terminology is confusing right now.
Merge pull request #2993 from Asana/react-0.12

React 0.12