Allow overriding Deleted Session folder name
Files:
sessionmanager/src/sessionmanager_bootstrap/chrome/content/modules/encryption_manager.jsm 1.2
sessionmanager/src/sessionmanager_bootstrap/chrome/content/modules/session_file_io.jsm 1.14
sessionmanager/src/sessionmanager_bootstrap/chrome/content/modules/session_manager.jsm 1.14
sessionmanager/src/sessionmanager_bootstrap/chrome/content/modules/utils.jsm 1.17