Tests have been randomly failing with messages like
listen tcp 127.0.0.1:51778: bind: address already in use
Rework all the test servers so they choose a random free port on
startup and use that for the tests to avoid.
The UPnP MediaServer spec says that the ConnectionManager service is
required, and adding it was enough to get dlna support working on my
other TV (LG webOS 2.2.1).
The SCPD URL was being set after marshalling the XML, and thus coming
out blank. Now works on my Samsung TV, and likely fixes some issues
reported by others in #2648.
