A first pass at a working tekton s2i and maven multi-step pipelines

[akochnev]

Added all the relevant changes needed for a working tekton pipelines

The maven multi-step pipeline still needs a couple more steps to deal with deploying to the staging/prod projects. In the current state, both pipelines succeed their initial run.

This is dependent on the following PRs getting merged first:

• Changes to the devsecops-api-script to allow working with nexus : https://github.com/jharmison-redhat/devsecops-api-script/pull/3
• Changes to the sample openshift-tasks app : https://github.com/jharmison-redhat/openshift-tasks/pull/1