Work on #404, updated class diagram and javadoc. Passed checkstyle checks

dao/pom.xml

@@ -47,6 +47,7 @@
     <dependency>
         <groupId>com.h2database</groupId>
         <artifactId>h2</artifactId>
+        <scope>compile</scope>
       </dependency>
     <dependency>
       <groupId>de.bechte.junit</groupId>