fix(ssh/timeout): Turn off use_dns setting from CoreOS and Deis-Builder

Currently the CoreOS and Deis-Builder uses the default setting for ssh which has use_dns turned on.
This causes unnecessary DNS lookups which slows down the SSH connection.

This PR turns off the UseDNS in the CoreOS User-data and on the Deis-Builder Dockerfile.

fixes #1358
not that I know of. Currently it ships with the other 2 lines.