Support ECR

[ThaoTrann]

#192
Use Amazon ECR credential helper.
Add binaries to kraken-origin, kraken-build-index, can add pre compiled binary (https://github.com/awslabs/amazon-ecr-credential-helper/releases) in Dockerfile
(e.g origin Docker)

FROM debian:9

RUN apt-get update && apt-get install -y curl sqlite3 nginx

RUN mkdir -p -m 777 /var/log/kraken/kraken-origin
RUN mkdir -p -m 777 /var/cache/kraken/kraken-origin
RUN mkdir -p -m 777 /var/run/kraken

ARG USERNAME="root"
ARG USERID="0"
RUN if [ ${USERID} != "0" ]; then useradd --uid ${USERID} ${USERNAME}; fi

COPY ./docker/setup_nginx.sh /tmp/setup_nginx.sh
RUN /tmp/setup_nginx.sh ${USERNAME}

USER ${USERNAME}

COPY ./origin/origin /usr/bin/kraken-origin
COPY ./config /etc/kraken/config
COPY ./nginx/config /etc/kraken/nginx/config
COPY ./localdb/migrations /etc/kraken/localdb/migrations
COPY ./test/tls /etc/kraken/tls

RUN apt-get update && apt-get -y install sudo

# Build amazon-ecr-credential-helper
RUN curl -Lo docker-credential-ecr-login https://amazon-ecr-credential-helper-releases.s3.us-east-2.amazonaws.com/0.3.1/linux-amd64/docker-credential-ecr-login && chmod +x docker-credential-ecr-login && sudo mv docker-credential-ecr-login /etc/kraken

WORKDIR /etc/kraken

Have one of the AWS credentials https://github.com/awslabs/amazon-ecr-credential-helper#prerequisites.
Add ecr backend support to config map.
eg. build_index

backends:
      - namespace: </.*>
        backend:
          registry_tag:
            address: 123456789012.dkr.ecr.us-west-2.amazonaws.com
            security:
               credsStore: 'ecr-login'

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[evelynl94]

thanks to @Rowern for the fix in makisu repo https://github.com/uber/makisu/tree/master/lib/registry/security
and @ThaoTrann for porting it over.