pushed the winstone dependency to the <dependencies> so that we can see the source code during debugging

earlier maven-hpi-plugin.

This is a proof of concept to core modulizarion (by binary integration.)
A module is built like a plugin but it's packaged to the war as a
WEB-INF/lib/*.jar, not as a plugin.

Compared to plugins, jars integrated in this way do not double-package
dependency jars, and they are not visible to the users. I plan to try a
few of these and if it's useful, this could be an useful mechanism for
modularizing core.

mappings.

Recording the earlier changes and the integration of the new
executable-war.

JENKINS-8658 depend on latest executable-war. This is where the fix should be. Note: of course one should release that dependency into a stable version

Since we've just changed the group ID and break everyone who depend on
the old artifact GAV, might as well rename artifact IDs as well.
(Otherwise we'd break people twice.)