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'
    }
});
```
@hellosmithy I believe @jasonLaster means a function that handles the actual logic of converting the `@ui.foo` type string to a selector.  So, you would have some function `parseUIString(uiString, ui)`  (not a great name) that handles the string regex replace.  With that abstracted out, we could then have `normalizeUIKeys` and `normalizeUIValues` both use the function instead of reimplementing the same logic.