Extract log_level from configuration file if the level was not
overridden by the command line option. The default command line
option is 1 and there is no command line option to set the
verbose_level to 1, so if it is 1, it has not be set.
Change-Id: I1be04367c72f83c1181f92ca4c2c83165b66995c
Implements: blueprint logging-migration