Perform OAuth flow in same window

This part is actually quite simple. I had to rearrange some of my application to cope with the different workflow.

I created an endpoint in my app, `/oauth/callback`, and an `OAuthCallbackController` to handle it. Then I created a simple HTML file for my redirect URI, similar to `oauth2callback.html` but instead of loading Angular, it simply manipulates the URL to make it compatible with "hashbang" routing and pass it along to the Angular endpoint:

```javascript
location.replace('/#/oauth/callback?' + location.hash.slice(1));
```

Then I'm able to access the OAuth params from my controller, set the token and all that good stuff:

```javascript
  .controller('OAuthCallbackController',
    function($scope, $rootScope, $location, $injector, VgerCredentials, Token, $timeout, flash, User, UserTrackingId) {
      var params = $location.search();
      Token.verifyAsync(params.access_token).
        then(function(data) { ... }
    });
```