Allow ssh from ls.test to ls.ext

To be able to run commands directly on ls.ext from tests, e.g. to reindex.
For now, must disable host identity checking.
Example:
  ssh -i ~/.ssh/insecure_private_key -o StrictHostKeyChecking=no -o PasswordAuthentication=no vagrant@192.168.50.10 -c <command>
Merge branch 'master' of github.com:digibib/ls.ext