Use STOPPED status to identify if machine is off

lib/vagrant-lxc/machine_state.rb

@@ -1,7 +1,7 @@
 module Vagrant
   module LXC
     class MachineState < Vagrant::MachineState
-      CREATED_STATES = %w( running poweroff ).map!(&:to_sym)
+      CREATED_STATES = %w( running stopped ).map!(&:to_sym)
 
       def initialize(state_id)
         short = state_id.to_s.gsub("_", " ")
@@ -14,7 +14,7 @@ module Vagrant
       end
 
       def off?
-        self.id == :poweroff
+        self.id == :stopped
       end
 
       def running?

spec/support/unit_example_group.rb

@@ -5,6 +5,7 @@ module UnitExampleGroup
       Object.any_instance.stub(:system) { |*args, &block|
         UnitExampleGroup.prevent_system_calls(*args, &block)
       }
+      require 'vagrant/util/subprocess'
       Vagrant::Util::Subprocess.stub(:execute) { |*args, &block|
         UnitExampleGroup.prevent_system_calls(*args, &block)
       }

spec/unit/machine_state_spec.rb

@@ -29,8 +29,8 @@ describe Vagrant::LXC::MachineState do
     it { should_not be_off }
   end
 
-  context 'when state id is :poweroff' do
+  context 'when state id is :stopped' do
-    subject { described_class.new(:poweroff) }
+    subject { described_class.new(:stopped) }
 
     it { should be_created }
     it { should be_off }