bug fix to copy_remote_file_to_nodes() which prevented passwordless-ssh as root

Was previously copying files from master back to master in the course of trying to enable passwordless ssh for root.
Merge branch 'vanilla_improvements' into vanilla-minor-fixes
Merge pull request #12 from pgm/vanilla-minor-fixes

Bug fix for problem with setting up passwordless ssh for root
Fixed merge error
Merge branch 'vanilla_improvements' of github.com:datacratic/StarCluster into vanilla_improvements
Merge branch 'vanilla_improvements' into datacratic_dev