Disallow importing "default" as a named import

[ljharb]

Babel allows import { default as Foo } from 'foo' - I'm not sure if the spec does too.

I'd like a rule that requires import { default as Foo, Bar } be written as import Foo, { Bar }.

[benmosher]

Last I checked, importing a default export as a name is valid ES6, but this seems like a reasonable style-guide rule.

Name: no-named-default?

[giodamelio]

This should be closed now that #596 is merged right?