added push unstable image (#2)

* added push unstable image

* added fullImageTag

* double escape string

* added returnStdout: true

* added grobidTag

* named parameters for sh

* using bash

* construct fullImageTag using grobidTag

* using `=` for ENV JAVA_OPTS for consistency

* added label

* check grobid tag

* print actual grobid label

* trim grobid tag

* escape $

* more escaping

* removed "-latest"

* removed -latest suffix

* temporarily use a docker-read-label version that doesn't pull

* log image

* temporarily don't run end-to-end example as part of ci

* echo echo

* removed single quotes just in case

* trying explicit toString()

* pass in full image tag

* added revision label

* revised revision

* added org.opencontainers.image.source

* enable example end-to-end again

* added comment to IMAGE_TAG