RFC: Warn if a compnent has an update() but no verify()

[frlan]

We have seen situations in a deployment, where there was an update() defined, by no verify(). Therefore update() will most likely never be executed. I think batou should issue a warning in such cases.

[elikoga]

We should warn on all the components that are mounted in the tree of .configure methods, some base classes have an update() method but no verify() method.