[MODEL] Added, that index settings/mappings can be loaded from a YAML or JSON file

This change allows you to specify a YAML file with settings for the indices.

It would be helpful if you want to reuse analyzers in many different indexes.

Also, YAML is much more readable than hashes in ruby code.

Example:

    # config/elasticsearch/custom_analyzers.yml
    #
    # number_of_shards: 5
    # analysis:
    #   analyzer:
    #     my_custom_analyzer:
    #       tokenizer: "whitespace"
    #       filter: ["lowercase", "asciifolding"]
    #

    class Article
      include Elasticsearch::Model

      settings "config/elasticsearch/custom_analyzers.yml"
    end

    class Author
      include Elasticsearch::Model

      settings "config/elasticsearch/custom_analyzers.yml"
    end

Closes: elastic#346
Closes: elastic#351

Author: David Padilla

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

@@ -153,7 +153,24 @@ def mapping(options={}, &block)
         #
         #     # => {:index=>{:number_of_shards=>1}}
         #
+        # You can specify a YAML file with settings
+        #
+        # @example Define index settings from YAML file
+        #
+        #     # config/elasticsearch/articles.yml:
+        #     #
+        #     # index:
+        #     #   number_of_shards: 1
+        #     #
+        #
+        #     Article.settings "config/elasticsearch/articles.yml"
+        #
+        #     Article.settings.to_hash
+        #
+        #     # => { "index" => { "number_of_shards" => 1 } }
+        #
         def settings(settings={}, &block)
+          settings = YAML.load_file(settings) if settings.is_a?(String)
           @settings ||= Settings.new(settings)
 
           @settings.settings.update(settings) unless settings.empty?

elasticsearch-model/test/support/model.yml

@@ -0,0 +1,2 @@
+baz:
+  'qux'

elasticsearch-model/test/unit/indexing_test.rb

@@ -28,13 +28,20 @@ class NotFound < Exception; end
         assert_instance_of Elasticsearch::Model::Indexing::Settings, DummyIndexingModel.settings
       end
 
-      should "update and return the index settings" do
+      should "update and return the index settings from a hash" do
         DummyIndexingModel.settings foo: 'boo'
         DummyIndexingModel.settings bar: 'bam'
 
         assert_equal( {foo: 'boo', bar: 'bam'},  DummyIndexingModel.settings.to_hash)
       end
 
+      should "update and return the index settings from a yml file" do
+        DummyIndexingModel.settings "test/support/model.yml"
+        DummyIndexingModel.settings bar: 'bam'
+
+        assert_equal( {foo: 'boo', bar: 'bam', 'baz' => 'qux'}, DummyIndexingModel.settings.to_hash)
+      end
+
       should "evaluate the block" do
         DummyIndexingModel.expects(:foo)