Add two more attributes to the model

[Damianofds]

The model Of the Timeseries layer should also include the following attributes that, of course, make sense only in case of a Vector layer:

• INCREMENTAL_LOADING indicates that the layer updates which compose this layer are ingested incrementally (f.e. province by province)
• PRIMARY_KEY in order to be able to remove inserted features that have to be updated

https://github.com/slms4redd/utils/blob/master/geostore/src/main/java/it/geosolutions/unredd/geostore/model/UNREDDLayer.java

[Damianofds]

This feature is not required anymore since the use case of the country which requested it have been changed.