Redesing the Contextual inforamtion forms

[ohernan]

Posible solution:

• Not naming it as Contextual Information in the layers form, maybe "Layer Information"
• Allowing textual new fields. Maybe someone would like to keep the description and the URL for the entities. Althought they don't want to used in the models.
• Showing the "Layer Information" in the "Properties form" in the Entities form (first tab), just before the Parents/Children info. It is fixed
• Maintain the Contextual Information only for the Customised Information for the entity. Maybe named as "Customised Information".

related to #131

[ohernan]

mentioned in issue #131

[ohernan]

Do we want to allow using the models requeted information also when the user defines contextual information at the layer level?

[ohernan]

Alberto: I think it makes sense to have it also for layers

Btw, we should think whether it is the case to drop the entity page
and have only one configuration page in which the user can configure
everything from layers to entities; because now there is a sort of
duplication that requires double effort to maintain.