add missing mocks

* mock for delete_group_policy request
* mock for delete_bucket_policy request
* mock for put_bucket_policy request

lib/fog/aws/requests/iam/delete_group_policy.rb

@@ -27,6 +27,23 @@ module Fog
           )
         end
       end
+
+      class Mock
+        def delete_group_policy(group_name, policy_name)
+          if !data[:groups].key? group_name
+            raise Fog::AWS::IAM::NotFound.new("The group with name #{group_name} cannot be found.")
+          elsif !data[:groups][group_name][:policies].key? policy_name
+            raise Fog::AWS::IAM::NotFound.new("The group policy with name #{policy_name} cannot be found.")
+          else
+            data[:groups][group_name][:policies].delete(policy_name)
+
+            Excon::Response.new.tap do |response|
+              response.body = { 'RequestId' => Fog::AWS::Mock.request_id }
+              response.status = 200
+            end
+          end
+        end
+      end
     end
   end
 end

lib/fog/aws/requests/storage/delete_bucket_policy.rb

@@ -21,6 +21,21 @@ module Fog
           })
         end
       end
+
+      class Mock
+        def delete_bucket_policy(bucket_name)
+           if bucket = data[:buckets][bucket_name]
+             bucket[:policy] = nil
+
+             Excon::Response.new.tap do |response|
+               response.body = { 'RequestId' => Fog::AWS::Mock.request_id }
+               response.status = 200
+             end
+           else
+             raise Fog::AWS::IAM::NotFound.new("The bucket with name #{bucket_name} cannot be found.")
+           end
+        end
+      end
     end
   end
 end

lib/fog/aws/requests/storage/put_bucket_policy.rb

@@ -20,6 +20,23 @@ module Fog
           })
         end
       end
+
+      class Mock
+        #FIXME: You can't actually use the credentials for anything elsewhere in Fog
+        #FIXME: Doesn't do any validation on the policy
+        def put_bucket_policy(bucket_name, policy)
+          if bucket = data[:buckets][bucket_name]
+            bucket[:policy] = policy
+
+            Excon::Response.new.tap do |response|
+              response.body = { 'RequestId' => Fog::AWS::Mock.request_id }
+              response.status = 200
+            end
+          else
+            raise Fog::AWS::IAM::NotFound.new("The bucket with name #{bucket_name} cannot be found.")
+          end
+        end
+      end
     end
   end
 end