Here we go... we can now, via balancer-manager, add new

Here we go... we can now, via balancer-manager, add new
workers to existing balancers. Still work to be done,
like error checking that we aren't trying to add more
than we can (right now, it fails, but it would be nice
to handle it nicer), disabling and *deleting* workers
we don't want anymore, the actual drain method, etc...
but this is some major goodness.

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1067269 13f79535-47bb-0310-9956-ffa450edef68