Fix exception on page load in BBL April update.

The new BBL April Release update now uses Tomcat6, which with all the
API updates, seems to have broken GroupBuilder.

Looks like the shortcut of object.method being short for
object.getMethod() now doesn't like it when method has the same name as
a Java keyword, so object.class doesn't work as object.getClass()
anymore. I've just added a getClassName() method to ManagedObject to be
used to get the class name instead.