Only do username mangling if variables set in config files.

fixes #312
Report more details during auth and logon.

refs #312
Report logout events to logfile.
Remove unrequired checks from userdir manager.

There is no real need to do all these checks for different reasons:

* The script is called with "create" anyway only if the user directory
  does not exist (see login.php, look for "createUserFolders").
* Calling "mkdir -p" for all required dirs is much more convenient than
  doing long checks - mkdir and chmod are much faster in figuring out if
  something needs to be done. Same goes for the "rm" command in the
  delete() function.

refs #309, #307
Report output from userdir helper script to logs.

refs #309