Adjust checkstyle rules. Make checkstyle fail the build when violations are found. Correct all current checkstyle violations.

facade/src/main/java/com/iluwatar/facade/DwarvenGoldmineFacade.java

@@ -16,6 +16,9 @@ public class DwarvenGoldmineFacade {
 
   private final List<DwarvenMineWorker> workers;
 
+  /**
+   * Constructor
+   */
   public DwarvenGoldmineFacade() {
     workers = new ArrayList<>();
     workers.add(new DwarvenGoldDigger());

facade/src/main/java/com/iluwatar/facade/DwarvenMineWorker.java

@@ -46,6 +46,9 @@ public abstract class DwarvenMineWorker {
     }
   }
 
+  /**
+   * Perform actions
+   */
   public void action(Action... actions) {
     for (Action action : actions) {
       action(action);