Fix python26 compatibility for RFCSysLogHandler

1)Currently used pattern will fail for Python 2.6.x.
In order to fix the broken Python 2.6.x compatibility,
old style explicit superclass method calls should be used instead.
Here is an example of how to check this for Python v2.7 and v2.6:
  import logging.handlers
  print type(logging.handlers.SysLogHandler)
  print type(logging.Handler)
Results would be:
  Python 2.7: <type 'type'>, so super() may be used for
    RFCSysLogHandler(logging.handlers.SysLogHandler)
  Python 2.6:<type 'classobj'>, so super() may *NOT* be used.
2)Add unit test for wrapped format().

Closes-bug: #1306559

Change-Id: Ib93daac4c3bd72107074be3df64005af1ff18acb
Signed-off-by: Bogdan Dobrelya <bogdando@mail.ru>