[MODEL] Added a HashWrapper class to wrap Hash structures instead of raw Hashie::Mash

Since Hashie now prints out a warning whenever a key which clashes with a built-in method
is added, such as `sort`, the logs are flooded.

Hashie has a `disable_warnings` method in hashie/hashie@b2f94a4 to supress
the logging, so a simple sub-class has been added to allow calling it cleanly,
and to serve as a possible extension point in the future.

Many thanks to @michaelherold for the pointers to a similar implementation
in the Omniauth gem and adding quickly the infrastructure in the Hashie gem!

Closes #666

Author: karmi

elasticsearch-model/lib/elasticsearch/model/hash_wrapper.rb

@@ -0,0 +1,15 @@
+module Elasticsearch
+  module Model
+
+    # Subclass of `Hashie::Mash` to wrap Hash-like structures
+    # (responses from Elasticsearch, search definitions, etc)
+    #
+    # The primary goal of the subclass is to disable the
+    # warning being printed by Hashie for re-defined
+    # methods, such as `sort`.
+    #
+    class HashWrapper < ::Hashie::Mash
+      disable_warnings if respond_to?(:disable_warnings)
+    end
+  end
+end

elasticsearch-model/test/unit/hash_wrapper_test.rb

@@ -0,0 +1,13 @@
+require 'test_helper'
+
+require 'hashie/version'
+
+class Elasticsearch::Model::HashWrapperTest < Test::Unit::TestCase
+  context "The HashWrapper class" do
+    should "not print the warning for re-defined methods" do
+      Hashie.logger.expects(:warn).never
+
+      subject = Elasticsearch::Model::HashWrapper.new(:foo => 'bar', :sort => true)
+    end if Hashie::VERSION >= '3.5.3'
+  end
+end