config: use raw strings instead of escaping
config: use raw strings instead of escaping

Fixes the flake8 E605 for the lines:

./config.py:264:34: W605 invalid escape sequence '\ '
./config.py:592:61: W605 invalid escape sequence '\ '
./config.py:596:-84: W605 invalid escape sequence '\ '

mesosphere/marathon-lb,vixns/marathon-lb,mesosphere/marathon-lb,vixns/marathon-lb,vixns/marathon-lb,mesosphere/marathon-lb