a8d38fb1f7bb733a968a263d6cdecc1e3f68f99f

The helloworld plugin is used to demonstrate features of the plugin API. Add it as a submodule so it's included in the tree. Thus we can make sure it's always buildable against the latest Gerrit code base. Change-Id: I1450ce02d04cf213eaeaaca0386a357d99423c4a
Description
RETIRED, Gerrit as used by OpenStack