SystemClassLoader enhancements

The ApplicationClassLoader is actually what the Sun docs refer to as the
SystemClassLoader. The RVM class should be renamed to reflect this change.

The ClassLoader should manage the java.class.path system property
internally. So all the command line parameters that modify the classpath
will route through the ApplicationClassLoader. Existing args such as -jar,
-classpath and -Djava.class.path= will be easy to redirect to this
classloader.

Currently jikes does not handle the -javaagent command line parameter
correctly. The jar should also be added to the system classloader AND
appended to the java.class.path system property.