Added Docker pipeline generate job, alternative Docker registry support and no-cache to docker build

[RobertNorthard]

This is dependent on PR#3 being merged.

• Added job to generate a new pipeline (parameters defaulted to use the ADOP tomcat reference Dockerfile).
  ** The trigger part of the Get_Dockerfile job only works with Gerrit but the pipeline can test Dockerfiles in arbitrary Git repositories e.g. GitHub. This can be corrected when the ADOP SCM pluggable library is added to the core.
• Added no-cache to docker build command to detect errors in which the images third-party dependencies are no longer accessible (e.g. package repository updates/versions added or removed).
• Added alternative Docker registry support
  ** Defaults to the public docker registry.
• Removed deprecated method in DSL injectPasswords()

Next steps;

• Add comprehensive tests.
• Validate generate job parameters (e.g. docker image tag regex).
• DOA instructions will need to be updated before being merged into the official repository.

[kramos]

Tested this, looks really good. I'll demo it tomorrow at Config Management camp!

Minor question: why do you need the git url and the git repo name? Can the repo name not always be extracted from the other?

[RobertNorthard]

@kramos thanks. I'm not to keen on the Git repo name either. It is used by the Gerrit trigger. I was going to factor it out when the SCM pluggable library had been integrated with the core as the library would deal with this.

[kramos]

It would be nice if the seed job got auto run with the defaults.