WL-1026 : announcements made on a .anon site should be public by default

(Not sure what happened with this code (which seems strangely familiar!)...so here it is again...)

This is to fix it so that when your site is public and you create an announcement, then when you select 'Public' in the dropdown, the announcement shows up. 

I'm using the isChannelPublic(channelId) method to determine whether a site is public or not and passing the value through