When commands are run in ktest, they are only displayed in the ktest log
file, but that is not sufficient for outputting the display for config
bisects. The result of a config bisect is not shown.

Add a way to display the output of "run_command" which is the subroutine
used by ktest to execute commands. Use this feature to display the output of
config-bisect.pl executions to see the progress as well as the result.
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>