Load configuration from a file.

Closes #5

@stefanpenner can do you want to have a look at the PR then I will push it to NPM.

#### With a config file
```handlebars
{{ember-spinner config='standard'}}
```
Add a folder to your app called `ember-spinner` with a file called `standard.js`

```javascript
export default {
  color:  blue,
  lines:  10,
  length: 30
}
```

Cheers
Dave