SpringAtom - #107

Initial commit of reworked approach for data utilities like converters for Domain object in SpringAtom:

PersistableConverter - extends Converter and ConditionalConverter to provide strict and type safe way of defining the converter which is capable of converting from Persistable object to its String representation
PersistableConverterImpl - default implementation of PersistableConverter that defines some reusable fields as well dynamically resolved generic attribute type which evaluates, in concrete implementations, to the source of conversion of particular PersistableConverter

PersistableConverterPicker is able to resolve converter:
- either default when there is no selector specified
or
- for given selector