Changes:
* The old internal `dmedia.httpd` WSGI HTTP server has finally been dropped, which was only still being used for the peering protocol; the peering protocol now uses a `degu.server.SSLServer` instance instead.
* The old WSGI applications for the peering protocol have been dropped, replaced by equivalent RGI applications for the Degu Server.
* The file downloader now directly uses `degu.client.SSLClient` instead of indirectly via `microfiber.CouchBase`; importantly, this means the file downloader can now use `degu.client.Connection.get_range()`, which means Dmedia doesn't have to carry its own functions for building HTTP Range headers.
* Update `dmedia.rgiapps` unit tests for the Degu 0.14 `Request.script` --> `Request.mount` attribute rename
* Fix an issue with the `dmedia-...