[api] raise rubygem versions to current state
[api] fix support for channel configurations with a project given in projectlist, but not per package.
[webui] Fix saving interconnects from /configuration
[backend] very basic support for publishing .exe files
[webui] Use Project.find_linking_projects to find linking projects
[api] fix removal of all _product:* package containers when _product gets deleted
refactor sync_to_stage

- also allow multiple stage servers and stage server partitioning
- also support a sync script
[api] avoid not reachable backend objects when package destroy throw an exception
[backend] support architecture specific update urls
[api][backend] rework Download on Demand feature

WARNING: still a remote root leak with chroot workers

WARNING: this is incompatible to expermintal DoD function in OBS 2.5 and before