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.
@cjyu Is this log message still necessary to have or can we remove it?

If we should keep it, we should make it shorter by removing some of the slashes so it fits on the previous line.