New developer documentation

[jamoore]

This requirement has been added to take some of the less critical documentation stories from #6296 for more immediate release. As discussed in Paris with a number of new developers coming onboard, both in Dundee and at various other sites, it will be critical to be able to get them up to speed quickly and painlessly. The primary output of this requirement should be a very small number of landing pages which a new developer (core, satellite, open-source) can be pointed out to find all the necessary information for getting started. This includes various tasks like uploading public keys, etc, basic OME/RO background information, commit procedures and testing requirements, and then how to start learning the appropriate APIs.

See #6296

Content copied from #6948 "Working with code base"

Umbrella ticket for defining

• code style/policy.
• enforcing copyright.
• Define header of files.
• define how to work with github
• how to work with tools like Eclispe, Pycharm
• etc.

Build process (previously #6951)

• integration of insight build. see #3940
• training material
  • where to put it.
  • maintenance.
  • when to build
  • etc.
• Let devs only build they need e.g. B-F, insight

Branch merging (previously #6934)

• In order to have continuous integration of active branches before they are merged into develop, we will need to have jobs which take properly marked branches from all github forks, merge them into a single branch, and then test that branch.
• Moving to future for us to investigate when we again have multiple branches / PRs all simultaneously active. The hope would be that such a build would prevent us from having to manually push to merge-green / merge-blue. Any merge failures would be detected immediately.

See #2125. Those stories should likely be added here as tickets.