Add support to specify which docker image version to run

[kgalli]

It is often necessary to run a different version of a particular docker image in development to test a Pull Request or similar. To deal with this you have to update the docker-compose / cliw config every time you need this change. Furthermore, it is very easy to get confused which version is running write now. Not to mention that when you need to run several different versions in a kind of testing environment it is unnecessarily complicated to automate the change of the configuration. I recommend adding a feature like cliw service:origin to be able to overwrite the version.

"buildOrigin": {
  "registry": {
    "image": "kgalli/api-service:<This PART IS CHANGABLE VIA CONFIG>"
  }
}