Signo integration - pre split - do not merge

PR is ready to be merged, please review squashed commits. It's quite large so I'd be happy if someone actually test it.

after repo split PRs:
* https://github.com/Katello/katello/pull/2106
* https://github.com/Katello/katello-installer/pull/1

This one is to be removed when splitted PRs are merged