Allow the Byteman agent to be installed at runtime if possible

Sun#s JVM provides a capability to upload a Java agent at runtime rather than having to provide it on the Java command line using the -javaagent option. This feature makes ad hoc rule upload much easier to perform. Unfortunately, it is not possible to do this on all JVMs. Hoiwever, it would be nice if it were possible to use this feature on JVMs which implemented the dynamic agent capability.