DON'T MERGE YET I HAVE AN IDEA feat(statusTags): Implement page/breadcrumb tags

Some of our products have been putting ALPHA and BETA tags
into page titles and breadcrumbs by making use of ng-bind-html
in the appropriate name/title fields. This PR formalizes that
as part of the framework.

We've added optional labels to `<rx-page>` via the `status` attribute,
and to breadcrumbs via the `status` attribute.

The framework currently ships with `"alpha"` and `"beta"` tags. If there
is demand for more general ones in the future, we can add those.

This also adds support for per-product custom tags. Products can use
`rxStatusTagsProvider.addStatus` in their `.config()` methods, and then
freely use that status tag in their product.

Closes #638

![screen shot 2014-12-09 at 4 55 07 pm](https://cloud.githubusercontent.com/assets/9376/5366723/340d1d04-7fc4-11e4-8ddd-c706b69cffeb.png)

![screen shot 2014-12-09 at 4 55 16 pm](https://cloud.githubusercontent.com/assets/9376/5366725/3a6b98ce-7fc4-11e4-86d3-4148fb7da371.png)

Since you are in the context of a `.then` callback, you don't need to pack up your own promise.

```js
title: {
    get: function () {
        var page = this;
        return this.lblTitle.isPresent().then(function (present) {
            return present ? page.lblTitle.getText() : null;
        });
    }
},
```

I chose `null` in this case because I typically will use it for the cases where it simply doesn't exist.