Use https and http appropriately when connecting to MusicBrainz

Fixed some bugs:
- MusicBrainz submit URL always has https as protocol: hardcoded, even when
inappropriate. It's just a graphical issue.
- Whipper appears to always communicate with MusicBrainz using musicbrainzngs
over http. The musicbrainzngs.set_hostname(server).
- `musicbrainzngs.set_hostname(server)` always defaults to http. Since musicbrainzngs
version 0.7 the method `set_hostname` takes an optional argument named `use_https`
(defaults to False) which whipper never passes.

Changed behaviour of `server` option (`musicbrainz` section of whipper's configuration file).
Now it expects an URL with a valid scheme (scheme must be `http` or `http`, empty scheme isn't allowed anymore).
Only the scheme and netloc parts of the URL are taken into account.

Fixes #437.

Signed-off-by: JoeLametta <JoeLametta@users.noreply.github.com>

whipper/image/table.py

@@ -351,7 +351,7 @@ class Table:
         return disc.id
 
     def getMusicBrainzSubmitURL(self):
-        host = config.Config().get_musicbrainz_server()
+        serv = config.Config().get_musicbrainz_server()
 
         discid = self.getMusicBrainzDiscId()
         values = self._getMusicBrainzValues()
@@ -363,7 +363,7 @@ class Table:
         ])
 
         return urlunparse((
-            'https', host, '/cdtoc/attach', '', query, ''))
+            serv['scheme'], serv['netloc'], '/cdtoc/attach', '', query, ''))
 
     def getFrameLength(self, data=False):
         """