Merge branch 'improve_logging' into is24-master

* improve_logging:
  fixup NullHandler for python2.6
  adding tox testing for python2.6 and python 2.7
  check that deactivation of log file rotation works
  update comment
  add docstrings to the unit-tests
  improve tests
  adding test file for logger
  midnight should be a string
  fix import
  make log rotation configurabel
  configure renderingLogger metricAccessLogger via function
  configure cacheLogger via function
  configure exceptionLogger via function
  configure infoLogger via function
  introduce a function to configure loggers
  reconfigure the metricAccessHandler
  configure NullHandlers in case logging is not requested