Always show share/edit/etc to reduce jumpiness

Re-introduce the flash messages when attempting to reply to and
share unsaved annotations. Doing so is better than hiding them
because hiding them results in newly created annotations changing
layout when the id is returned from the server.

h/static/scripts/directives/annotation.coffee

@@ -153,6 +153,9 @@ AnnotationController = [
     # Creates a new message in reply to this annotation.
     ###
     this.reply = ->
+      unless model.id?
+        return flash 'error', 'Please save this annotation before replying.'
+
       # Extract the references value from this container.
       {id, references, uri} = model
       references = references or []
@@ -170,6 +173,8 @@ AnnotationController = [
     # Toggle the shared property.
     ###
     this.toggleShared = ->
+      unless model.id?
+        return flash 'error', 'Please save this annotation before sharing.'
       @shared = not @shared
 
     ###*