use newer chef-hub to install git-core
mosh package currently missing
don't mount disk if its missing
[openstack] If server has no ephemeral then /dev/vdb device used
volume now mounted at ~/bosh-workspace
no more gems from https://s3.amazonaws.com/bosh-jenkins-gems/
Merge pull request #56 from cloudfoundry-community/skip-mount-if-missing

attached disk improvements