* commit '49b90a93':
  ZP-739 Use sprintf() in log message.
  ZP-739 The guideline of the project state that the private function must start by a lowercase. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-739 Enforce the maximum value for PING_HIGHER_BOUND_LIFETIME and PING_LOWER_BOUND_LIFETIME to 3540. Released under the Affero GNU General Public License (AGPL) version 3.
  ZP-739 Implemtent ping higher and lower bound. Released under the Affero GNU General Public License (AGPL) version 3.