OHAI-542 defined cloud_v2 plugin interface object

replaced PR #251

Cloud_v2 Plugin
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The `node['cloud_v2']` plugin is available to provide consistent access to server configurations typically managed by IaaS (aka "cloud"") environments. Since the `node['cloud']` structure can vary from cloud-to-cloud it has been deprecated. Use the `node['cloud_v2']` in your recipes when you intend for it to work in multiple IaaS environments.

Migrating to the cloud_v2 plugin:
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* **GCE Specific Recipes**: the `node['cloud']['public_ipv4']` and `node['cloud']['local_ipv4']` attributes are no longer arrays in the cloud_v2 plugin, but are strings representing the first NICs reported. Use `node['cloud_v2']['public_ipv4_addrs']` and `node['cloud_v2']['local_ipv4_addrs']`, respectively, if you still need an Array of all NICs available to VM.

* **Azure Specific Recipes**: the `node['cloud']` attributes are all Azure specific, use `node['azure']` instead.

* **All Clouds**: `node['cloud']['public_ips']` and `node['cloud']['private_ips']` are now deprecated to allow consistent naming for both IPv4 and IPv6 NICs. Use `node[:cloud_v2][:public_ipv4_addrs]` and `node[:cloud_v2][:local_ipv4_addrs]` instead.