Rearranged files to match route tree. Tests pass.

I rearranged some of the file structure to match the initiatives routes tree given in the Ember debugger. I made a routes/initiative/index.js file for the InitiativeIndexRoute and put the action for supporting the initiative here. Note that because InitiativeIndexRoute is a child of InitiativeRoute, you can't specify the model id here, it has to be done in the parent (c.f. http://stackoverflow.com/questions/24247000/resource-path-parameter-not-passed-to-route):

```
 model: function(params) {
    return this.store.find('initiative', params.initiative_id);
  }
```

I also put the `index.emblem` template for `/initiatives/:initiative_id`in `templates/initiative/` and the `index.emblem` for `/initiatives`in `templates/initiatives/`