Update responses from 0.5.1 to 0.6.1 (#2678)

requirements/dev.txt

@@ -16,7 +16,9 @@ WebTest==2.0.28 \
 
 mock==2.0.0 --hash=sha256:5ce3c71c5545b472da17b72268978914d0252980348636840bd34a00b5cc96c1
 
-responses==0.5.1 --hash=sha256:3a907f7aae2fd2286d06cfdf238957786c38bbcadc451adceecc769a4ef882b7
+responses==0.6.1 \
+    --hash=sha256:6669409d475fb439577dd10d9e40389fd00ee074cb4fe2b829d0ac223324815f \
+    --hash=sha256:f9485ab2c9380b85f98ee15ed28fc9f6e4911082acec28b1e42c60f19935bf19
 
 django-extensions==1.8.1 \
     --hash=sha256:b29373cc2dd087d978166c2183f272db77a0dace565ba6393bbffed7ce7344aa \