CLOUDSTACK-7143: initial apt-upgrade still running out of space (upgrading the kernel)

I wonder if this is due to the 7.4.0->7.6.0 needing more space. Should see if
there's more stuff that can be cleaned earlier?
CLOUDSTACK-7143: fix the fix for rvm/ruby/bundler setup on jenkins

The recommended use of --deployment goes along with the requirement to
check Gemfile.lock into source control, which I don't want to do.
CLOUDSTACK-7143: fix do_signature to account for change to install_cloud_scripts

The do_signature script required a lingering cloud-scripts.tar that was no longer
there after the git export tarball fiddling magic was gone.