Add initial disk builtin action

lib/vagrant/action.rb

@@ -15,6 +15,7 @@ module Vagrant
       autoload :Confirm, "vagrant/action/builtin/confirm"
       autoload :ConfigValidate, "vagrant/action/builtin/config_validate"
       autoload :DestroyConfirm, "vagrant/action/builtin/destroy_confirm"
+      autoload :Disk, "vagrant/action/builtin/disk"
       autoload :EnvSet,  "vagrant/action/builtin/env_set"
       autoload :GracefulHalt, "vagrant/action/builtin/graceful_halt"
       autoload :HandleBox, "vagrant/action/builtin/handle_box"

lib/vagrant/action/builtin/disk.rb

@@ -9,10 +9,25 @@ module Vagrant
 
         def call(env)
           machine = env[:machine]
+          defined_disks = get_disks(machine, env)
+
+          # Check that provider plugin is installed for disk
+          # If not, log warning or error to user that disks won't be managed
 
           # Continue On
           @app.call(env)
         end
+
+        def get_disks(machine, env)
+          return @_disks if @_disks
+
+          @_disks = []
+          @_disks = machine.config.vm.disks.map do |disk|
+            # initialize the disk provider??
+          end
+
+          @_disks
+        end
       end
     end
   end

plugins/providers/virtualbox/action.rb

@@ -79,6 +79,7 @@ module VagrantPlugins
           b.use ForwardPorts
           b.use SetHostname
           b.use SaneDefaults
+          b.use Disk
           b.use Customize, "pre-boot"
           b.use Boot
           b.use Customize, "post-boot"