active_machines should return name as a symbol

lib/vagrant/environment.rb

@@ -168,7 +168,7 @@ module Vagrant
         # If this isn't a directory then it isn't a machine
         next if !name_folder.directory?
 
-        name = name_folder.basename.to_s
+        name = name_folder.basename.to_s.to_sym
         name_folder.children(true).each do |provider_folder|
           # If this isn't a directory then it isn't a provider
           next if !provider_folder.directory?

test/unit/vagrant/environment_test.rb

@@ -43,7 +43,7 @@ describe Vagrant::Environment do
       machine_bar = machines.join("bar/virtualbox")
       machine_bar.mkpath
 
-      instance.active_machines.should == [["foo", :virtualbox]]
+      instance.active_machines.should == [[:foo, :virtualbox]]
     end
   end