Improve destination matching when processing requests

Each time a SOAP request message is processed, the proper destination among those available in the Bus associated to the ws application has to be selected. Currently, we iterate over all destinations to find one that matches the requested path. We could improve this by trying looking up the destination in a map (path->destination) and fall back to iteration only if no exact match is possible (for instance because the proper endpoint has been declared with a "/*" url-pattern in web.xml).