v3(service): Fix validation message so that tags can be requested for the SO of SI.

[#155025477](https://www.pivotaltracker.com/story/show/155025477)

Author: FelisiaM

app/messages/service_instance_show_message.rb

@@ -8,7 +8,7 @@ class ServiceInstanceShowMessage < BaseMessage
         'space' => %w(name guid),
         'space.organization' => %w(name guid),
         'service_plan' => %w(name guid),
-        'service_plan.service_offering' => %w(name guid description documentation_url),
+        'service_plan.service_offering' => %w(name guid description tags documentation_url),
         'service_plan.service_offering.service_broker' => %w(name guid)
       }
     }

app/messages/service_instances_list_message.rb

@@ -28,7 +28,7 @@ class ServiceInstancesListMessage < MetadataListMessage
         'space' => %w(guid name relationships.organization),
         'space.organization' => %w(name guid),
         'service_plan' => %w(guid name relationships.service_offering),
-        'service_plan.service_offering' => %w(name guid description documentation_url relationships.service_broker),
+        'service_plan.service_offering' => %w(name guid description documentation_url tags relationships.service_broker),
         'service_plan.service_offering.service_broker' => %w(name guid)
       }
     }

spec/unit/messages/service_instance_show_message_spec.rb

@@ -10,7 +10,7 @@ module VCAP::CloudController
 
     it_behaves_like 'field query parameter', 'service_plan', 'name,guid'
 
-    it_behaves_like 'field query parameter', 'service_plan.service_offering', 'name,guid,description,documentation_url'
+    it_behaves_like 'field query parameter', 'service_plan.service_offering', 'name,guid,description,tags,documentation_url'
 
     it_behaves_like 'field query parameter', 'service_plan.service_offering.service_broker', 'name,guid'
 

spec/unit/messages/service_instances_list_message_spec.rb

@@ -83,7 +83,7 @@ module VCAP::CloudController
 
         it_behaves_like 'field query parameter', 'service_plan', 'guid,name,relationships.service_offering'
 
-        it_behaves_like 'field query parameter', 'service_plan.service_offering', 'name,guid,description,documentation_url,relationships.service_broker'
+        it_behaves_like 'field query parameter', 'service_plan.service_offering', 'name,guid,description,documentation_url,tags,relationships.service_broker'
 
         it_behaves_like 'field query parameter', 'service_plan.service_offering.service_broker', 'name,guid'
       end