[SAC] script to delete LDAP users

[Sandro Santilli]

Until we find a better way to block spam users (ideally marking
them as blocked, in a way that ldapserach can distinguish
blocked from still active) I've added a /osgeo/tools/ldap/ldap_delete_user
script in the "web" machine. It takes root privilege to run, shows uid
info before asking for confirmation. Also gives 10 seconds of time to kill
the process in case it was issued on error.

The list of people who can invoke the script, at the moment
(being those who are in the "sudo" group):

  sbarnes
  tmitchell
  warmerdam
  hobu
  martin
  wolf
  crschmidt
  neteler
  aboudreault
  jharahush
  jgrocha
  dwaetjen
  ian
  wildintellect
  jmckenna
  arnulf
  strk

--strk;