Prep work for isolating audio package.

src/Discord.Net.Commands/CommandServiceConfig.cs

@@ -1,5 +1,4 @@
-using Discord.Commands.Permissions;
-using System;
+using System;
 
 namespace Discord.Commands
 {
@@ -40,7 +39,7 @@ namespace Discord.Commands
 		protected void SetValue<T>(ref T storage, T value)
 		{
 			if (_isLocked)
-				throw new InvalidOperationException("Unable to modify a discord client's configuration after it has been created.");
+				throw new InvalidOperationException("Unable to modify a service's configuration after it has been created.");
 			storage = value;
 		}
 	}