Add version info to debug output

[AlexanderAmelkin]

• Initialize the log at the start of ipmi_main() to allow for proper
  logging at the start;
• Remove the unused log_level_get() function;
• Update log_level_set() to take verbosity instead of log level
  (default verbosity is 0, which is LOG_NOTICE log level),
  use the function to update log level as -v is encountered
  in command line;
• Move IANA PEN list debugging to verbosity 6. The list is too long
  to see it in each debug output of verbosity 5 that is used for
  debugging lan/lanplus packets;
• For verbosity >= 2 (that is -vv) add the ipmitool version
  information at the start.

Signed-off-by: Alexander Amelkin alexander@amelkin.msk.ru