Pass ip/names to be added to the hostfile

* script reads a comma separated lists of IP/server names.
* Add this to your .env.{staging production} to use:
`HOST_FILE_ENTRIES="10.91.10.10 server.example.com,10.91.10.11 server2.example.com"`
Merge pull request #17 from amaabca/add-entries-to-hostfile

Pass ip/names to be added to the hostfile