Sync the wfs_conf_select_client from geoportal.rlp into trunk

[armin11]

The wfs_conf select client gets a wfs_conf id from the get-api and handels a list of wfs_confs which are shown as a dropdown menu. Selecting a entry of this menu opens either a wfs gazetteer or the generic wfs client which allows a selection and download of the features. The features are converted to some predefined formats and will be send as a zip file.