Redo CANVAS-206 (remove EtherPad deletion warning)

A previous change was overwritten by a merge of tag
'tags/release/2013-07-13.24'.

Previous commit: 86ec8194ce446d6c9530ef9e98c128ca4253a51a
Overwriting commit: 72566073a9e15a81e33ea4b668ac457bc6a72813