`named` rule not working

Hi,

First off, thanks for the great plugin. The `named` rule doesn't seem to be working for me (at least as expected) while others do.

## Context

### `package.json`
```
$ egrep 'eslint-.*import' package.json

"eslint-import-resolver-webpack": "^0.8.3",
"eslint-plugin-import": "^2.7.0",
```

### `.eslintrc`

```
{
"parser": "babel-eslint",
...
"settings": {
...
"import/resolver": {
"webpack": {
"config": "webpack.prod.config.js"
}
}
},
...
"extends": [
...
"plugin:import/errors",
"plugin:import/warnings"
],
"rules": {
"max-len": ["error", 80, 2, { "ignoreUrls": true }],

// Don't warn us about using console.log (though that should only
// happen in the dev environment).
"no-console": [0]
},
...
}
```

## Issue

I've got a file with the following contents

```js
import { logToSentry, butts } from './errors'

const errorAlert = (msg, err) => {
logToSentry(msg, err);
butts();
}
```
As you can probably imagine, `butts` doesn't exist in `./errors` and certainly isn't `export`ed. Eslint raises no issue about this.

However, I know that `eslint-plugin-import` is doing *something* because if I change `./errors` to a path that doesn't exist, I get the following output from eslint:

```
/code/actions.jsx
5:36 error Unable to resolve path to module './errorsDoesntExist' import/no-unresolved

✖ 1 problem (1 error, 0 warnings)

```

So why would one rule be working (`import/no-unresolved`) but not the other (`import/named`)? Any guidance is much appreciated.

Reproduce the report using the package.json dependencies, .eslintrc settings, and webpack.prod.config.js resolver configuration. Compare the behavior of import/no-unresolved and import/named for the shown ./errors import, then verify that named reports the non-exported butts binding without breaking valid imports.

Written by the indexing model from the issue text.