Adding Response#add_audio_stop

`when 'AMAZON.PauseIntent' then output.add_audio_stop`

Author: charlotte-miller

fixtures/response-sessionAudioStop.json

@@ -0,0 +1,12 @@
+{
+  "version" : "1.0",
+  "response" :
+  {
+    "directives": [
+      {
+        "type": "AudioPlayer.Stop"
+      }
+    ],
+    "shouldEndSession": true
+  }
+}

lib/alexa_rubykit/response.rb

@@ -39,6 +39,10 @@ def add_audio_url(url, token='', offset=0)
       }
     end
 
+    def add_audio_stop
+      @directives << { 'type' => 'AudioPlayer.Stop' }
+    end
+
     def add_reprompt(speech_text, ssml = false)
       if ssml
         @reprompt = { "outputSpeech" => { :type => 'SSML', :ssml => check_ssml(speech_text) } }

spec/response_spec.rb

@@ -123,4 +123,12 @@
     expect(response_json).to eq(sample_json)
   end
 
+  it 'should create a valid response with an AudioPlayer.Stop directive' do
+    response = AlexaRubykit::Response.new
+    response.add_audio_stop
+    response.build_response_object
+    response_json = response.build_response
+    sample_json = JSON.parse(File.read('fixtures/response-sessionAudioStop.json')).to_json
+    expect(response_json).to eq(sample_json)
+  end
 end