Refactoring of specs

* split the one large spec file in multiple small, one for each model
* helper for getting dump object in tests

spec/support/helpers.rb

@@ -0,0 +1,11 @@
+module Refinery::WordPress::SpecHelpers
+  def test_dump
+    file_name = File.realpath(File.join(File.dirname(__FILE__), '../fixtures/wordpress_dump.xml'))
+    Refinery::WordPress::Dump.new(file_name) 
+  end
+end
+
+RSpec.configure do |config|
+  config.include Refinery::WordPress::SpecHelpers
+end
+