Explicitly declare serialVersionUID in LogMutation class

The LogMutation class doesn't have its serialVersionUID defined as a private final static constant hence the compiler generates one for it. Upon every logMutation call, the existing logMutation objects are collected from the chosen config store and deserialized, but if a new/different RM jar loads these and the serialVersionUIDs don't match (for example a different compiler generated a different ID) an InvalidClassException occurs.