Lambda layer for utilizing the Sharp image manipulation library
It is important that the Sharp dependency is installed for Linux x64, which is what AWS Lambda runs on:
$ npm install --arch=x64 --platform=linux --target=10.15.0 sharphttp://sharp.pixelplumbing.com/en/latest/install/#aws-lambda
Creates an export named SharpLambdaLayer that can be referenced within other CF templates.