Pass release env variables to dapper
We're using the release procedure from shipyard, which needs these env
variables available inside the dapper.
FROM quay.io/submariner/shipyard-dapper-base
-ENV DAPPER_ENV="REPO TAG" \
+ENV DAPPER_ENV="REPO TAG QUAY_USERNAME QUAY_PASSWORD TRAVIS_COMMIT" \
DAPPER_SOURCE=/go/src/github.com/submariner-io/submariner DAPPER_DOCKER_SOCKET=true
ENV DAPPER_OUTPUT=${DAPPER_SOURCE}/output
