Reword thanks-confirmation and thanks-thanked-notice

* Make thanks-confirmation more neutral dropping "Are you sure":
  That "are you sure" is disturbing, it makes it look something disruptive.
  People only wanted some confirmation step, not a dissuading barrier.
* Reword thanks-thanked-notice from "told" to "notified" per Siebrand.

Change-Id: I06fa57d7f77b297caf9d3267513365481992b67b