`isolated-container` should  call `resolver.normalize(fullName)` when resolving needs values.

This caused an issue for us when using the ES6 resolver and entities with more than one name which are dasherized. Here's an example of something that was previously problematic:

```
moduleForComponent('tags-edit', 'Unit: Component tags-edit', {
  needs: [
    'controller:tagItem',
    'component:bc-text',
    'template:components/bc-text'
  ]
});
```

In this case, I was using an `itemController` for an `{{each}}` within my component. The each helper in my template will always try to look up the value as camel case (as is convention). However, because I'm using the ES 6 resolver, all names are dashized on the filesystem. So prior to this change, no attempt was made to allow the resolver to normalize the value before looking it up. IE there was no way for 'controller:tag-item' to be registered as 'controller:tagItem'.

I don't anticipate this being a breaking change, even for those using the ES6 resolver.