mounting and getting the bower object

[faassen]

When you have a root app and an app mounted in it, and the root app derives from the StaticApp, and the app mounted in it uses the static_components directive, more.static will fail to include things. The problem is that the root app tries to get the bower object through the components registered with static_components, but nothing is registered, and thus nothing happens. We didn't have this problem when we used the WSGI-based bower.wrap(), as this included the information on which bower object to use.

One workaround is to set a 'bower' class-level variable on the root app to the bower object used. But this requires a global. Another workaround would be to define a static_components for the root using the same bower as the sub-apps use.

None of these are really nice. We need to think of something better.