Replace custom tab manager with ngView

[justmoon]

Right now we are using a custom TabManager class for loading and rendering tabs instead of the native Angular ngView. We did this originally because of certain limitations in Angular.js.

[justmoon]

One thing that Angular does not currently support is nested views:

angular/angular.js#1291

We are currently only using nested views for one thing: Tabs that have a menu and sub-tabs. We can probably refactor that so that it doesn't actually use nested views, but rather just include the menu html on each individual tab.

We're also using a dirty hack for making the injector extensible:

angular/angular.js#1721

Ideally, the Angular team would finish the hierarchical injector. But as far as I can tell our hack still works fine even if we switch to ng-view.