Remove dependence on V1 Kernel from Environment

lib/vagrant/config/v1.rb

@@ -76,6 +76,10 @@ module Vagrant
         # Get all the registered plugins
         config_map = {}
         Vagrant.plugin("1").registered.each do |plugin|
+          # Activate the plugin since we're about to use it
+          plugin.activate!
+
+          # Get all the available configuration keys and add them to the map
           plugin.config.each do |key, klass|
             config_map[key] = klass
           end

lib/vagrant/environment.rb

@@ -422,7 +422,7 @@ module Vagrant
       # to simply be our configuration.
       if defined_vm_keys.empty?
         defined_vm_keys << DEFAULT_VM
-        defined_vms[DEFAULT_VM] = VagrantPlugins::Kernel::VagrantConfigSubVM.new
+        defined_vms[DEFAULT_VM] = nil
       end
 
       vm_configs = defined_vm_keys.map do |vm_name|