Reorg collected traits so that they can be reasonably displayed

X-Runtime, X-Version - we currently collect them as wikipedia https://en.wikipedia.org/wiki/List_of_HTTP_header_fields suggests that it contains "version details" related to X-Powered-By. A more detailed query shows that this is not the most usual case. X-Runtime seems to be rather used for application's response time in seconds and X-Version for versioning of REST APIs. We should stop collecting both X-Runtime and X-Version.

X-Aspnet-Version should be stored as a suffix of the delivered X-Powered-By value.

Having all the above, only two traits fields are left: Server and X-Powered-By. Given that the UI (see the mock in https://issues.jboss.org/browse/HAWKULAR-226) will not display the two separatelly, it makes no sense to store them in separate fields that would have to be joined together by the UI.