Fix for #105: Updated HadoopSecurityManager_H_2_0.java and ant build file

This PR includes the updated HadoopSecurityManager_H_2_0.java and moved a few classes in azkaban.security.commons to its own directory so they can be used in both hadoopsecuritymanager and hadoopsecuritymanager-yarn.
It would be good to pass the exception as a parameter to the HadoopSecurityManagerException constructor.