[New] add jsx-quoted-string-props rule

[rkusa]

Implements #529. Enforce quoted props for string-typed property values.

Bad:

<div id={'foobar'} />

Good:

<div id="foobar" />

Since this is the first ESLint rule I've ever implemented, feel free to be picky, feedback is highly welcome!

[golopot]

It seemed that this feature is already implemented in jsx-curly-brace-presence.

https://github.com/yannickcr/eslint-plugin-react/blob/35de81b7b47f92b3a1b20e34269df15de462adb6/tests/lib/rules/jsx-curly-brace-presence.js#L411-L418

[rkusa]

Even better - Thanks for pointing the existing one out!