Make jbanking serializable-friendly

[marcwrobel]

Serialization in java is a difficult thing to master and should be avoided if possible (see also Effective Java 3rd edition - Item 85 : Prefer alternatives to java serialization). Despite that, many classes in jbanking, such as Iban, Bic, CreditorIdentifier..., are good candidates for default serialized form.

Those classes should implement Serializable in order to make some parts of jbanking usable with :

• frameworks that relies on serialization,
• exceptions (the java.lang.Exception extends Serializable),
• servlet containers (the servlet specification requires that all objects stored in the session be serializable),
• ...