Adding a path attribute to the vm_mob_ref hash

This patch adds a new `path` attribute to the vm_mob_ref hash returned
by the `convert_vm_mob_ref_to_attr_hash` method. In order to support the
new `path` attribute, this patch also adds a new `get_folder_path` method
to the `list_virtual_machines` vsphere module.

lib/fog/vsphere/compute.rb

@@ -58,6 +58,7 @@ module Fog
             attrs['mo_ref'] = vm_mob_ref._ref
             attrs['hypervisor'] = attrs['host'].name
             attrs['mac_addresses'] = vm_mob_ref.macs
+            attrs['path'] = get_folder_path(vm_mob_ref.parent)
           end
         end
 

lib/fog/vsphere/models/compute/server.rb

@@ -33,6 +33,7 @@ module Fog
         attribute :is_a_template
         attribute :connection_state
         attribute :mo_ref
+        attribute :path
 
         def start(options = {})
           requires :instance_uuid

lib/fog/vsphere/requests/compute/list_virtual_machines.rb

@@ -75,6 +75,13 @@ module Fog
           end
           results.flatten
         end
+
+        def get_folder_path(folder, root = nil)
+          if ( not folder.methods.include?('parent') ) or ( folder == root )
+            return
+          end
+          "#{get_folder_path(folder.parent)}/#{folder.name}"
+        end
       end
 
       class Mock