[digitalocean] Add support for private networking

lib/fog/digitalocean/models/compute/server.rb

@@ -17,6 +17,7 @@ module Fog
         # Not documented in their API, but
         # available nevertheless
         attribute :public_ip_address, :aliases => 'ip_address'
+        attribute :private_ip_address
         attribute :backups_active
 
         attr_writer :ssh_keys
@@ -124,6 +125,9 @@ module Fog
           elsif @ssh_keys
             options[:ssh_key_ids] = @ssh_keys.map(&:id)
           end
+
+          options[:private_networking] = !!attributes[:private_networking]
+
           data = service.create_server name,
                                        flavor_id,
                                        image_id,

lib/fog/digitalocean/requests/compute/create_server.rb

@@ -24,6 +24,8 @@ module Fog
             query_hash[:ssh_key_ids] = options[:ssh_key_ids]
           end
 
+          query_hash[:private_networking] = !!options[:private_networking]
+
           request(
             :expects  => [200],
             :method   => 'GET',

tests/digitalocean/models/compute/server_tests.rb

@@ -6,8 +6,8 @@ Shindo.tests("Fog::Compute[:digitalocean] | server model", ['digitalocean', 'com
 
     tests('have the action') do
       test('reload') { server.respond_to? 'reload' }
-      %w{ 
-        shutdown 
+      %w{
+        shutdown
         reboot
         power_cycle
         stop
@@ -19,12 +19,13 @@ Shindo.tests("Fog::Compute[:digitalocean] | server model", ['digitalocean', 'com
 
     tests('have attributes') do
       model_attribute_hash = server.attributes
-      attributes = [ 
+      attributes = [
         :id,
         :name,
         :state,
         :backups_active,
         :public_ip_address,
+        :private_ip_address,
         :flavor_id,
         :region_id,
         :image_id,