Pita/etherpad-lite — pull request #939 by marcelklehr (2012-08-10 11:23:20+00:00)
Title: Create group2sessions.sessionIDs if it doesn't exist yet.

This attempts to fix a bug, that caused a server shutdown in [#787](https://github.com/Pita/etherpad-lite/issues/787#issuecomment-7597618).