Add some core team review stats
Add some core team review stats

Show the total number of reviews done by the core team, as well as the
core team size.

Change-Id: I2ac64a24d44d557191bdebba031239a390fb4c69

cp16net/reviewstats,cp16net/reviewstats,openstack-infra/reviewstats,openstack-infra/reviewstats,JohnGarbutt/reviewstats,JohnGarbutt/reviewstats