BasicManagement:2 implementation update

[Jussi Kukkonen <jussi kukkonen intel com>]

Hi all,

This is an update on the UPnP BasicManagement / DLNA DIAGE proposal.
The wip/basic-management branch has been (force) udpated to match the
below description.

I've fixed some bugs in the past week, modified commit messages to fit
rygel style and made one architectural change -- partly based on
feedback, partly because I had missed that the service may also be
used on mediaservers (within DIAGE spec). Quoting from the commit
message:
    Remove the coupling to MediaRenderer: allow BasicManagement on any
    rygel plugin, provided the configuration specifies that diagnostics
    should be started.

    Add a "+DIAGE+" capability that is exposed in the device description
    when diagnostics is enabled.

    This change means that by default the service will not run. Add this to
    rygel.conf to enable:
      [Playbin]
      diagnostics=true

So there is a new configuration item, and if it is not set the service
will not be started, and the dlna capability is not advertized. If the
config item is set, Plugin will start the service and "+DIAGE+" is
added to dlna capabilities.

I can't think of any more blocker issues. I'm ready to modify things
of course but I'm hoping this is complete enough to make a decision on
whether to merge or not -- I still think it's a good idea but I could
be biased :)

Cheers,
  Jussi