[MODEL] Stop requiring empty block for setting mapping options

This just bit me when trying to configure a class that includes Elasticsearch::Persistence::Model. Since the attribute definitions handle setting up the mapping, I just wanted to set dynamic and _routing. I had to resort to debugging to find out that I had to pass an empty block to get the #mapping method to actually do something with my options.

Closes elastic#393

Author: ryansch

elasticsearch-model/lib/elasticsearch/model/indexing.rb

@@ -133,9 +133,9 @@ module ClassMethods
         def mapping(options={}, &block)
           @mapping ||= Mappings.new(document_type, options)
 
-          if block_given?
-            @mapping.options.update(options)
+          @mapping.options.update(options) unless options.empty?
 
+          if block_given?
             @mapping.instance_eval(&block)
             return self
           else

elasticsearch-model/test/unit/indexing_test.rb

@@ -106,8 +106,8 @@ class NotFound < Exception; end
       end
 
       should "update and return the index mappings" do
-        DummyIndexingModel.mappings foo: 'boo' do; end
-        DummyIndexingModel.mappings bar: 'bam' do; end
+        DummyIndexingModel.mappings foo: 'boo'
+        DummyIndexingModel.mappings bar: 'bam'
         assert_equal( { dummy_indexing_model: { foo: "boo", bar: "bam", properties: {} } },
                       DummyIndexingModel.mappings.to_hash )
       end