providers/docker: use new b2d box

plugins/providers/docker/hostmachine/Vagrantfile

@@ -1,26 +1,3 @@
 Vagrant.configure("2") do |config|
-  config.vm.box = "mitchellh/boot2docker"
+  config.vm.box = "hashicorp/boot2docker"
-
-  config.vm.provider "virtualbox" do |v|
-    # On VirtualBox, we don't have guest additions or a functional vboxsf
-    # in TinyCore Linux, so tell Vagrant that so it can be smarter.
-    v.check_guest_additions = false
-    v.functional_vboxsf     = false
-  end
-
-  ["vmware_fusion", "vmware_workstation"].each do |vmware|
-    config.vm.provider vmware do |v|
-      if v.respond_to?(:functional_hgfs=)
-        v.functional_hgfs = false
-      end
-    end
-  end
-
-  # b2d doesn't support NFS
-  config.nfs.functional = false
-
-  # b2d doesn't persist filesystem between reboots
-  if config.ssh.respond_to?(:insert_key)
-    config.ssh.insert_key = false
-  end
 end