Excluding grub command line option for power
Excluding grub command line option for power

This change was required as we noticed that the openstack based base images were failing to boot up successful vm instances - in spite of it showing vm instance as "running" state on the openstack dashboard. 

The instance was repeatedly rebooting and I couldn't find any errors. So I got on the console and just adjusted the
kernel boot line taking out "console=ttyS0" and "quiet"  and for some reason doing that caused it to boot up normally. Narrowed down that this was happening due to this command line option here ..

# git  grep "GRUB_CMD"
cookbooks/travis_docker/files/default/etc/default/grub.d/99-travis-settings.cfg:GRUB_CMDLINE_LINUX="cgroup_enable=memory swapaccount=1 apparmor=0 console=ttyS0"

So removing this option will help vm instances boot up successfully.
travis-ci/travis-cookbooks,travis-ci/travis-cookbooks,travis-ci/travis-cookbooks