Updating CHANGELOG for the new validate_certs feature

Also removing validate_cert option from the cloudformation module docs,
as it does not use the standard ec2 connection.

cloud/cloudformation

@@ -88,14 +88,6 @@ options:
     required: false
     aliases: ['aws_region', 'ec2_region']
     version_added: "1.5"
-  validate_certs:
-    description:
-      - When set to "no", SSL certificates will not be validated for boto versions >= 2.6.0.
-    required: false
-    default: "yes"
-    choices: ["yes", "no"]
-    aliases: []
-    version_added: "1.5"
 
 requirements: [ "boto" ]
 author: James S. Martin