Remove vendored vagrant leftovers from specs

spec/spec_helper.rb

@@ -8,7 +8,7 @@ if ENV['COVERAGE']
   end
 end
 
-require 'bundler'
+require 'bundler/setup'
 
 require 'rspec-spies'
 

spec/unit/container/cli_spec.rb

@@ -1,6 +1,6 @@
 require 'unit_helper'
 
-require "vendored_vagrant"
+require 'vagrant'
 require 'vagrant-lxc/container/cli'
 
 describe Vagrant::LXC::Container::CLI do

spec/unit/container_spec.rb

@@ -1,6 +1,6 @@
 require 'unit_helper'
 
-require "vendored_vagrant"
+require 'vagrant'
 require 'vagrant-lxc/container'
 
 describe Vagrant::LXC::Container do