Upgrade of maven plugins (#951)

* Upgrade maven plugins

* Upgrade maven plugins

Some general code cleanup was necessary due to upgrade of PMD and checkstyle.

Also needed to add Junit 4 as a dependency due to Mockito.timout issue found here:
https://github.com/mockito/mockito/issues/152

service-layer/src/main/java/com/iluwatar/servicelayer/common/BaseEntity.java

@@ -25,10 +25,9 @@ package com.iluwatar.servicelayer.common;
 import javax.persistence.Inheritance;
 import javax.persistence.InheritanceType;
 import javax.persistence.MappedSuperclass;
-import javax.persistence.Version;
 
 /**
- * 
+ *
  * Base class for entities.
  *
  */
@@ -36,9 +35,6 @@ import javax.persistence.Version;
 @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
 public abstract class BaseEntity {
 
-  @Version
-  private Long version;
-
   /**
    * Indicates the unique id of this entity
    *