This is based on watching another person building Jenkins for the first
time.

This reverts commit 604e7e07.

Revert "menu needs to be explicitly inherited"

This reverts commit 7add578b.

Revert "Push Maven site to another repository"

This reverts commit 71d8014b.

This wasn't in there because of the historical reason.
The original layout didn't have the plugin parent POM under the core
source tree.

integrating a fix that's made in remoting.