Updated the cloud9-startup.sh to download and install latest version …

[desaiajayhnr]

Updated the cloud9-startup.sh to download and install latest version of eksctl

Updated the yelb-appserver-v2/Dockerfile charging the gem install flag from --no-ri --no-rdoc to --no-document, installed zlib1g , zlib1g-dev and puma packages

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Description of changes:

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[desaiajayhnr]

Hi Team,

While following the blogpost : https://aws.amazon.com/blogs/containers/getting-started-with-app-mesh-and-eks/ encountered the errors.

1. As the eksctl version in the walkthroughs/eks-getting-started/cloud9-startup.sh was hard coded to 0.19.0-rc.1, the eksctl was trying to create cluster with version 1.15 and the walkthroughs/eks-getting-started/infrastructure/create_eks.sh was failing. Updated the #Install eksctl step to download the latest version of the eksctl
2. As the script walkthroughs/eks-getting-started/build-appserver-v2.sh was failing at the docker build step. Replaced the --no-ri --no-rdoc to --no-document in the walkthroughs/eks-getting-started/yelb-appserver-v2/Dockerfile
3. Docker build was also failing for "cannot find -lz" error. Installed zlib1g and zlib1g-dev packages
4. After the step 2and 3, the container was crashing because the puma package was missing. Added the step to install puma package

Regards, Ajay