Added DAO pattern.

dao/src/main/java/com/iluwatar/BaseEntity.java

@@ -0,0 +1,27 @@
+package com.iluwatar;
+
+import javax.persistence.Column;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.Version;
+
+@Entity
+public class BaseEntity {
+
+	@Id
+	@GeneratedValue
+	@Column(name = "ID")
+	private Long id;
+
+	public Long getId() {
+		return id;
+	}
+
+	public void setId(Long id) {
+		this.id = id;
+	}
+	
+	@Version
+	private Long version;
+}