Fix 500 when saving /site/edit without email When saving /site/edit with no no_reply_email set, a 500 error page would be returned due to an empty value being passed as value to the datastore (which is not allowed for email fields).

# Geo-enabled Sitemap classes.
from django.contrib.gis.sitemaps.georss import GeoRSSSitemap
from django.contrib.gis.sitemaps.kml import KMLSitemap, KMZSitemap