[rackspace] simplify servers mock/real with shared module

lib/fog/rackspace/models/servers/flavors.rb

@@ -5,13 +5,7 @@ module Fog
   module Rackspace
     module Servers
 
-      class Real
-        def flavors
-          Fog::Rackspace::Servers::Flavors.new(:connection => self)
-        end
-      end
-
-      class Mock
+      module Collections
         def flavors
           Fog::Rackspace::Servers::Flavors.new(:connection => self)
         end

lib/fog/rackspace/models/servers/images.rb

@@ -5,15 +5,7 @@ module Fog
   module Rackspace
     module Servers
 
-      class Real
-        def images(attributes = {})
-          Fog::Rackspace::Servers::Images.new({
-            :connection => self
-          }.merge!(attributes))
-        end
-      end
-
-      class Mock
+      module Collections
         def images(attributes = {})
           Fog::Rackspace::Servers::Images.new({
             :connection => self

lib/fog/rackspace/models/servers/servers.rb

@@ -5,13 +5,7 @@ module Fog
   module Rackspace
     module Servers
 
-      class Mock
-        def servers
-          Fog::Rackspace::Servers::Servers.new(:connection => self)
-        end
-      end
-
-      class Real
+      module Collections
         def servers
           Fog::Rackspace::Servers::Servers.new(:connection => self)
         end

lib/fog/rackspace/servers.rb

@@ -5,6 +5,8 @@ module Fog
       class Error < Fog::Errors::Error; end
       class NotFound < Fog::Errors::NotFound; end
 
+      module Collections; end
+
       def self.new(options={})
 
         unless @required
@@ -47,6 +49,7 @@ module Fog
       end
 
       class Mock
+        include Collections
 
         def self.data
           @data ||= Hash.new do |hash, key|
@@ -75,6 +78,7 @@ module Fog
       end
 
       class Real
+        include Collections
 
         def initialize(options={})
           credentials = Fog::Rackspace.authenticate(options)