Include kramdown in Test Group
Include kramdown in Test Group

Travis tests are failing due to a lack of the `kramdown` gem. This will
ensure that Travis builds work (or at least don't fail for this
reason). May replace this with a load guard around that line.

hamadata/aws-sdk-ruby,takeyuweb/aws-sdk-ruby,aws/aws-sdk-ruby,takeyuweb/aws-sdk-ruby,cjyclaire/aws-sdk-ruby,cjyclaire/aws-sdk-ruby,takeyuweb/aws-sdk-ruby,hamadata/aws-sdk-ruby,cjyclaire/aws-sdk-ruby,hamadata/aws-sdk-ruby,aws/aws-sdk-ruby,llooker/aws-sdk-ruby,llooker/aws-sdk-ruby,llooker/aws-sdk-ruby,aws/aws-sdk-ruby