Enhancement serialVersionUID + prefix to payload options

[fl0l0u]

1. Implements #182 by overwriting final payload bytes. Attempts to implement a cleaner override using Unsafe or Reflection failed on Object with undefined serial. Usage -s org.apache.commons.beanutils.BeanComparator=-3490850999041592962
2. Adding feature for prepending arbitrary data to payload. Example payload generated with -p writeUTF=foo -p writeBoolean=true will reach gadget chain deserialization on following code:

String componentId = ois.readUTF();
boolean cancelAction = ois.readBoolean();
ComponentAction action = (ComponentAction) ois.readObject();