Add custom parameters for Map Center (lonlat + zoom)

Add some custom parameters to set initial map extent with
- center (lon/lat)
- zoom

Those paremeters can be overwrited in ovr file.
The defaults ones are :

    geofenceGlobalConfiguration.mapCenterLon=10.0
    geofenceGlobalConfiguration.mapCenterLat=32.0
    geofenceGlobalConfiguration.mapZoom=3