Revert "Remove temporary session folder code (bug #817940)"
This reverts commit 8e8132fb. That commit was not ready to be merged. As it says in the commit message, "if the session directory goes away somehow between updates, there is currently _no_ way to restore it without one of these two options. This may need to be considered before merging in this change." We can revert this revert when we have a good alternative for creating the session directories. Change-Id: I5141832da3225e202feef19dccabfea9ff35beeb