test: fix pep8 compliance in doombot script

daemon/test/doombot/README.md

daemon/test/doombot/doombot.py

daemon/test/doombot/gdb_wrapper.py

daemon/test/doombot/process_watcher.py

daemon/test/doombot/server.py

daemon/test/doombot/sflphone.py

daemon/test/scripts/stress_test.py