Fix some Checkstyle issues

- Remove unused imports
- Fix issues relating to line length / whitespace
- Update Checkstyle suppression in matcher classes with new check name

src/main/java/fr/xephi/authme/service/BukkitService.java

@@ -14,9 +14,7 @@ import org.bukkit.command.CommandSender;
 import org.bukkit.configuration.file.YamlConfiguration;
 import org.bukkit.entity.Player;
 import org.bukkit.event.Event;
-import org.bukkit.plugin.Plugin;
 import org.bukkit.scheduler.BukkitRunnable;
-import org.bukkit.scheduler.BukkitScheduler;
 import org.bukkit.scheduler.BukkitTask;
 
 import javax.inject.Inject;