improve notification when you send friend requests

- match the prompted action changing from "invite" to "add friends"
- say "request processing" rather than invitations have been queued for each
  person the user added, which may not be true if some of the people were
  already lantern users, or if the user invited more people than she had
  invites (#768), or if there is some other edge case
- tell the user the people she added will show up on the map when she connects
  to them successfully