Remove `vagrant down` (was deprecated in 0.3.0 to 0.3.2)

lib/vagrant/commands/down.rb

@@ -1,16 +0,0 @@
-module Vagrant
-  class Commands
-    # `vagrant down` is now `vagrant destroy`
-    class Down < Base
-      Base.subcommand "down", self
-
-      def execute(args=[])
-        error_and_exit(:command_deprecation_down)
-      end
-
-      def options_spec(opts)
-        opts.banner = "Usage: vagrant down"
-      end
-    end
-  end
-end

templates/errors.yml

@@ -45,9 +45,6 @@
   vagrant box add name uri
   vagrant box remove name
   vagrant box list
-:command_deprecation_down: |-
-  `vagrant down` is now `vagrant destroy`. Please use that command instead. This
-  warning will be removed in future versions.
 :dotfile_error: |-
   The dotfile which Vagrant uses to store the UUID of the project's
   virtual machine already exists and is not a file! The dotfile is