added jsx-uses-react rule

[lukeschunk]

Adds this rule https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/jsx-uses-react.md

Which will allow us to write pure functional components without directly referencing React in the file.

[paniclater]

Shouldn't every pure functional component reference React to leverage prop types?

[lukeschunk]

@paniclater for now, yes, but this change will be necessary to upgrade to the latest version of react in which PropTypes is its own package, and you don't refeference it off of React anymore

edit we also have this rule https://github.com/yannickcr/eslint-plugin-react/blob/master/docs/rules/prop-types.md to check to make sure we're doing props validation, if that is a concern.

[paniclater]