avoid NPE if a graph is not available yet
initial spike of #790 - needs some CSS polish and so far only shows the groups / profiles / brokers / containers; doens't show clients/producers/consumers
fix little gremlin in the durable subscriber view (Core.$apply() is your friend in async code ;); also open the dialog async; which probably isn't required but you never know ;). Also used checkbox for selection so that clicking the link doesn't select as well (leading to multiselections when trying to view detail); we could maybe just disable multi-select; but then that could be handy for deleting a lot of subscriptions?