[Dev] Sharing invitation sending asyncness

[Bryan Stearns]

Brian,

Currently, when we send sharing invitations, the messages are sent 
asynchronously; the sharing code doesn't have a way of finding out 
whether the sending was successful (and therefore, no way to help the 
user adjust to a mailing or addressing failure).

I'm thinking that the sharing-invitation generation stuff should move 
into the UI layer: the UI layer (specifically, 
MainView.onShareItemEvent, or something factored out from it) would 
create the message objects, initiate sending, wait for sending to 
complete or fail, then examine the message to check success. What do you 
think?

...Bryan