Allow jsx info strings

[IanVS]

The code blocks in jsx-quotes would be better expressed as jsx rather than js

js:

<a b='c' />

jsx:

<a b='c' />

But this would require supporting jsx info strings in this plugin. Ideally, would the pre-processor also be able to add the jsx ecmaFeature? Otherwise, linting of these will need to wait until eslint/eslint#3698.

[btmills]

I don't think it's possible for a preprocessor to alter configuration, so let's wait for the comment there. However, we can definitely add jsx to the list of info strings.