Request: create lambda from docker image GCR

[teebu]

AWS recently announced docker image support for lambdas.

https://aws.amazon.com/blogs/aws/new-for-aws-lambda-container-image-support/

API
https://docs.aws.amazon.com/lambda/latest/dg/API_FunctionCode.html#SSS-Type-FunctionCode-ImageUri

But would be nice if node-lambda would also build, tag and push to ECR.