Support experimental object spread

Object spread is an experimental feature, however, React encourages its use and as such it is one of the most commonly requested features. While this does not mean we will start supporting experimental features, we will make an exception because this keeps coming up as holding back React users from using ESLint out of the box.

The feature should be named experimentalObjectRestSpread and allow this syntax:

let { ...foo } = bar;
let foo = { a, ...b };

Full spec: https://github.com/sebmarkbage/ecmascript-rest-spread

[ilyavolodin]

@bradwestfall http://eslint.org/docs/user-guide/configuring#specifying-parser-options you are looking for experimentalObjectRestSpread

[bradwestfall]

Thank you