refactor printing the supported OSes message into a function
use the freebsd port for rubygem-chef

The newest ohai (6.16.0) has some problems finding the ipaddress  on freebsd.
add _configure_fabric_for_platform method

Pass in the `platform` property from Ohai to this method, and it will configure fabric for that platform.

Right now it only changes env.shell to `/bin/sh -c` if the platform is freebsd.

We call _configure_fabric_for_platform from the _node_runner method, and from the deploy_chef task
When deploying chef to a new node, create a node config file

If one doesn't already exist, create a node configuration file with some properties from ohai (ipaddress, platform, platform_family, and platform_version right now).

This is useful we we can perform some basic logic in littlechef based on these properties (e.g. changing env.shell for FreeBSD)