import/default failing on import of json file

Code:

``` javascript
import data from './data'
```

Relevant config:

``` javascript
"import/default": 2,
```

Error:

```
error No default export found in module
```

I'm not 100% certain, but I believe that node will allow importing of `json` files when the new module syntax is implemented. So this appears to be an error.

Start with the import/default rule and reproduce the reported `import data from './data'` case using the shown `"import/default": 2` configuration and a JSON file. Check how the rule identifies module exports and how JSON imports are expected to behave. Done means the expected JSON import behavior is established and covered by a regression test without an erroneous default-export error.

Written by the indexing model from the issue text.