grumpy with cosign validation

This code allows to use cosign with validating admission controllers for verifying the integrity of images.

Build from scratch

1. cosign generate-key-pair && cat cosign.pub | base64 -w0 - Copy this text to kubernetes secret, public in _manifest_.yaml
2. Build the docker image from scratch docker build . -t $IMAGENAME && docker push $IMAGENAME or use rewanthtammana/build:cosign
3. Generate certificates & perform deployments with, ./deploy.sh
4. Check the status
5. I have already signed an image & pushed it to my dockerhub. For validation run,
   1. Deploy Singed Image - kubectl run --rm -it rewanthtammana/python:alpine
   2. Deploy Unsigned Image - kubectl run --rm -it nginx