#9060: fix ellipsoid selection from srs

It is related with bug #9060 (http://hub.qgis.org/issues/9060) and weird behabior detected in issue #7441 (http://hub.qgis.org/issues/7441#note-4)

Changes:
+ Fix selection of ellipsoid from active srs in QgsProjectProperties dialog
+ filter ellipsoid list to only load items without duplicates