detect when unwanted remote is empty and remove it

Needs fixes to build when the webapp is disabled.

Remote.hs

@@ -28,6 +28,7 @@ module Remote (
 	byCost,
 	prettyPrintUUIDs,
 	prettyListUUIDs,
+	prettyUUID,
 	remoteFromUUID,
 	remotesWithUUID,
 	remotesWithoutUUID,
@@ -159,6 +160,10 @@ prettyListUUIDs uuids = do
 	  where
 		n = finddescription m u
 
+{- Nice display of a remote's name and/or description. -}
+prettyUUID :: UUID -> Annex String
+prettyUUID u = concat <$> prettyListUUIDs [u]
+
 {- Gets the remote associated with a UUID.
  - There's no associated remote when this is the UUID of the local repo. -}
 remoteFromUUID :: UUID -> Annex (Maybe Remote)