created CustomValue factory

spec/factories/custom_value_factory.rb

@@ -0,0 +1,16 @@
+FactoryGirl.define do
+  factory :custom_value do
+    custom_field
+    value ""
+
+    factory :principal_custom_value do
+      custom_field :factory => :user_custom_field
+      customized :factory => :user
+    end
+
+    factory :issue_custom_value do
+      custom_field :factory => :issue_custom_field
+      customized :factory => :issue
+    end
+  end
+end