Remove code paths for older vagrant.

Since previous commits have broken compatiblilty with vagrant versions
older than 1.4, this commit removes code supporting those versions.
Merge pull request #148 from sciurus/1.4_only

Remove code paths for older vagrant.
Using ssh info directly without shelling out

- The `vagrant ssh_config` command was including the `Host` option, which for
  OpenSSH_6.5p1 at least is throwing an error:
  ```
  Host directive not supported as a command-line option
  ```

- Also changing the local bind_address in the ssh command to 'localhost'
  instead of '0.0.0.0' in order to not expose the VM to other hosts on the host
  machine's network.  If this is desired, then the user can manually override
  it in the Vagrantfile config for port forwarding.
Merge pull request #150 from keitwb/port_forward_fix

Using ssh info directly without shelling out