V2.2 regions normalize ui

New branch for issue #1649

Adds support for @ui.syntax selectors in regions hash.

For example:

```
var layoutView = Backbone.Marionette.LayoutView.extend({
    regions: {
        foo: '@ui.bar'
    },
    ui: {
        bar: '.baz'
    }
});
```
I prefer `pattern.test(uiString)`.

Better yet, what if we nix the test?  The replace won't run unless there is a match anyway.