updated readme

bumped license year
removed unnecessary import

src/main/java/com/jagrosh/jmusicbot/Bot.java

@@ -42,7 +42,6 @@ import net.dv8tion.jda.core.entities.VoiceChannel;
 import net.dv8tion.jda.core.events.ReadyEvent;
 import net.dv8tion.jda.core.events.ShutdownEvent;
 import net.dv8tion.jda.core.hooks.ListenerAdapter;
-import net.dv8tion.jda.core.utils.PermissionUtil;
 import net.dv8tion.jda.core.utils.SimpleLog;
 import org.json.JSONException;
 import org.json.JSONObject;