MODE-2259 Fixed the WebApp handlers.

Since the requirement is to be able to deploy WARs from within our EAP subsystem, the only way I was able to figure out how to do this is via the `DeploymentAddHandler` which only works in the `MODEL` stage.

The solution was to check in our handlers the `requiresRuntime(context)` and only perform the model change & invoke the handler for a "NORMAL" server.
I can add an `assert requiresRuntime`, but I don't see the value.  
I don't want to tie ourselves with the WF API any more than strictly needed (remember EAP 6.1/6.2). Therefore, since all the handlers are implemented around the notion of "runtime", I'd rather keep that. As opposed to the fact that right now the implementation calls `context.isNormalServer()`