Fixes Checkstyle problems

There are few checkstyles problems found in the  which are required to be fixed

model-view-presenter/src/main/java/com/iluwatar/model/view/presenter/FileLoader.java

@@ -36,7 +36,7 @@ import org.slf4j.LoggerFactory;
  * <p>
  * It is responsible for reading and loading the contents of a given file.
  */
-public class FileLoader implements Serializable{
+public class FileLoader implements Serializable {
 
   /**
    * Generated serial version UID

model-view-presenter/src/main/java/com/iluwatar/model/view/presenter/FileSelectorPresenter.java

@@ -30,7 +30,7 @@ import java.io.Serializable;
  * <p>
  * It is responsible for reacting to the user's actions and update the View component.
  */
-public class FileSelectorPresenter implements Serializable{
+public class FileSelectorPresenter implements Serializable {
 
   /**
    * Generated serial version UID

model-view-presenter/src/main/java/com/iluwatar/model/view/presenter/FileSelectorView.java

@@ -28,7 +28,7 @@ import java.io.Serializable;
  * This interface represents the View component in the Model-View-Presenter pattern. It can be
  * implemented by either the GUI components, or by the Stub.
  */
-public interface FileSelectorView extends Serializable{
+public interface FileSelectorView extends Serializable {
 
   /**
    * Opens the view.