Support locally-defined patches

Branched off of https://github.com/pathable/quilt/pull/3, but happy to re-open if we decide against the name-change. (Is there a better way to make a PR that branches off an existing PR?)

Perhaps this idea has been thought about when deciding where to declare patches, but I've found this to be a nice solution when needing domain-specific views in multiple places (but not *everywhere*), ie:

```html
<label>If user submits an invalid response, go to:</label>
<select data-actions></select>

<label>If user submits valid response, go to:</label>
<select data-actions></select>
```

And then:

```coffeescript
class Actions extends Quilt.View
  render: ->
    # render @collection specifically for BotGenerator ...

class BotGenerator extends Quilt.View
  patches:
    actions: (el, options) ->
      new Actions({el, collection: @actions})
```