Issue 13 dockerfile

[jerusdp]

Issue #13
Updated Dockerfile to use AWS Lambda docker from the AWS public ecr repository.

This base offers the following advantages:

• actively updated by Amazon
• supports both x86 and arm (Graviton2) processors

Two additional changes in Dockerfile based on recommended best practices

• set -0 pipefail on curl and build to ensure that there isn't "false success"
• COPY instead of ADD as we are only copying the files

@zamazan4ik