WebSession: fix for list of admin activities

* Adds a missing if-statement to tmpl_account_adminactivities()
  thus fixing the "Configure BibKnowledge" activity link to be bound
  to the "cfgbibformat" action rather than the "cfgbibknowledge" one.
  (closes #1444)

Reported-by: Sebastian Witowski <sebastian.witowski@cern.ch>
Reviewed-by: Tibor Simko <tibor.simko@cern.ch>