Implement spread attributes

In relation to https://github.com/jsdf/coffee-react-transform/issues/19
Roughly as specified in https://github.com/facebook/react/commit/e6134c307e2bb7765aaa747eb5d2136fc18abbd7
On further consideration, with the current loose parser there isn't really an easy way to prevent this while still supporting this case: https://github.com/facebook/react/blob/e6134c307e2bb7765aaa747eb5d2136fc18abbd7/vendor/fbtransform/transforms/__tests__/react-test.js#L426