Add vCloud Gems

This commit adds the following vCloud supporting Gems to the Gemfile:

- vcloud-walker
- vcloud-core
- vcloud-edge_gateway
- vcloud-tools
Add YAML file for vcloud-launch

vcloud-launch requires a YAML file in order to build the box in question. This
commit adds the YAML file.
Add Jenkins scripts

To that end, this commit adds a Jenkins script to (a) create the machine using
`vcloud-launch`, (b) configure NAT and fireall rules on the vSE using
`vcloud-edge_gateway`.
Add bootstrap file

This commit adds a bootstrap file to the 'common' folder.
Add README for network configuration

A rather self-explanatory commit, I hope, which adds a README explaining how
things in the vcloud/net folder work.
Add Edge Gateway firewall and NAT rule config file

This commit adds an Edge Gateway firewall and NAT rule configuration file. The
syntax is, hopefully, self-explanatory, however full documentation can be found
in the `vcloud-edge_gateway` repository's README on GitHub.
Add interfaces.yaml file

In order to ensure that the edge gateway can be configured correctly, the
interfaces file is required. This commit adds only one interface file for
Carrenza - the interface attached to the Edge Gateway in the BACKUP vDC.
Add YAML to create Org vDC networks

This commit adds a YAML file in order to create org vDC networks. Org vDC
networks are required in order to ensure traffic from a vDC can be routed via an
Edge Gateway.
Add generate_fogfile.sh

In order to generate a Fog file to act as a credential store for
vCloud tools when credentials are user-specific and are not stored in any
centralised data store, we need to create a way to dynamically produce a Fog
file.

This commit adds a shell script which truncates the end of `fog_cred.config`
with new, default, values based on the environment variables passed to it by the
user (which are passed to Jenkins at deploy time).
Merge pull request #21 from alphagov/vcloud

Add supporting vCloud tools