Module developer workflow: including an unreleased module build

[ncoghlan]

We need to define a way for module developers to use the Boltron images as a test bed for:

• new modules that they're in the process of defining
• updated versions of existing modules

There are two pre-release build environments we want to consider:

• COPR module builds
• entirely local builds using mbs-build local

What are their next steps to actually make that module available to a running Boltron container so they can run through the steps in https://github.com/container-images/boltron-27#checking-specific-f27-modules?

[ncoghlan]

@james-antill's updates to support docker run --rm -it \ jamesantill/boltron-bikeshed /LOCAL.sh postgresql:9.6:20171018083530 reminded me that there's a third pre-release scenario to consider: updated modules that have been built in MBS, but not included in a successful base image compose yet.

So I think the first step here will be to add docs to the README on how to use that, and then look at COPR and mbs-build local support as a possible follow-up to that (since the download-and-create-a-local-repo steps should be at least somewhat similar).

Additional notes from James:

• you can add "/client" to the end to request an install profile other than the default
• the full list of available modules can be found at http://modularity.fedorainfracloud.org/modularity/mbs/

[ncoghlan]

I'm going to add the main docs for this to https://docs.pagure.org/modularity/development/building-modules/testing.html