Bump version to v1.3.6 for CoreOS Beta 494.4.0
Bump version to v1.3.7 for CoreOS Beta 494.5.0

- Docker v1.3.3
Set `config.ssh.insert_key = false` for Vagrant v1.7.x
Bump version to v1.3.8 for CoreOS Beta 494.5.0

- Set `config.ssh.insert_key = false` for Vagrant v1.7.x
Merge tag 'refs/tags/beta/v1.3.8' into stable
Bump version to v1.3.8 for CoreOS Stable 494.5.0