Root commit.
Readme driven development.

Explains the following sections:

- Overview
- Installation instructions
- Features
- How to contribute

It also adds a simple network configuration example.
Initial project structure.

Uses rvm to configure the development environment.

Adds the basic directory structure, that includes project files and unit
test spec files with line coverage.

It only adds the version file and specs.

It adds the following development dependencies:
- rake
- rspec
- simplecov
DSL implementation.

The DSL is implemented in three main file:
- machines
- dsl
- ssh

The DSL class defines the syntax of the DSL and constructs a new Network
instance. The Group instance represents a tree with the defined groups and it's
port forwardings. The Network instance contians an instance of the Gateway and
several local port Forwardings.

The options to build the Network instance are only used by the DSL class.

The Registry module implements some static methods to create and register
(define) new Network instances.

The Machines.load method uses the Kernel.load method to load machine definitions
stored in a particular directory. The fakefs gem is used to simulate the
existange of these machine definitions.

Adds the following dependencies:
- fakefs
SSH commands.

Adds ssh, tunnel, show and sshconfig commands to the SSH classes.
Command line parser.

The command line simply calls the SSH classes to do all the work.
Fix problem with more than one nested group, fixes #23.
Updates rubygems source.
Version bump.