Upgrade botocore to 1.3.16

Author: dstufft

requirements/main.txt

@@ -12,7 +12,7 @@ bcrypt==2.0.0
 billiard==3.3.0.22        # via celery
 bleach==1.4.2             # via readme-renderer
 boto3==1.2.3
-botocore==1.3.15          # via boto3
+botocore==1.3.16          # via boto3
 celery==3.1.19
 certifi==2015.11.20.1
 cffi==1.4.2               # via bcrypt