Fix rhq-28: Addtional configuration elements

- storage-adapter
- server-monitor
- diagnostics

In addition to that:

- updated readme
- improve service lifecycle


In my old implementation I have sent the full set of attributes if that was a map. This may be overkill, as e.g. heap.init "never" changes and heap.max only rarely. 
I still think it could be good to allow for that behavior as it reduces the number of `metric` elements if the user really wants all the attributes (and the internal dmr call picks up the full list anyway). But then there is also a cost associated.