Fix 500 when saving /site/edit without email
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).

rhyolight/nupic.son,rhyolight/nupic.son,rhyolight/nupic.son