Adds the save and load action using JIBX

## Adds the save and load action using JIBX.
For that, all the *ConfigurationAttributes* and the *GraphicalElements* were changed to make them compatible with the JIBX binding.

##### ConfigurationAttributes :
All of them were renamed to make the name representing the property they handle. The extends *BaseCE* or *BaseListCA* which implements all the common functions.
The *OwsContextCA* was also changed from *BaseCA* to *BaseListCA* (as it represents a list of OwsContext).
A factory for the CA is also added.

##### GraphicalElement :
All the GE need to extend a super class containing their CA to make it compatible with JIBX binding (*Document* need to extend *SimpleDocumentGE* which contain all the CA, *Scale* extends *SimpleScaleGE* ...).
Those extension can be avoir by doing a custom binding.

##### Other :
To permit the save, all the GE are contained in one object (*SaveHandler*) which implement all the functions for the marshalling and unmarshalling.

Then few corrections are done to improve the behaviour.
Remove this message dialog. Use SLF4J instead