build with latest pxe images
resolve rubocop complaints
use https for upstream, not ssh

Externals should be able to use non-authenticated access
to fetch upstream changes.
use latest lxc-docker in wercker
adjust rspec for changes in latest docker-api gem

    s/config/ContainerConfig/
show os-release in wercker
add coreos stable to pxe menu
git ignore the .git dirs
rspec: avoid timeout on wercker

we don't need to redirect stdin during rspec to cat a file.