SQLFeatureStore fetches all properties of a feature

[lgoltz]

Currently all properties of a features are fetched from database. This behaviour sometimes introduces some overhead and performance loss.

see: http://osgeo-org.1560.x6.nabble.com/Rendering-takes-too-long-between-deegree2-and-deegree3-td5144950.html

[tfr42]

deegree 2 did offer the functionality to select specific properties of a feature.