Cpp 145

First whack at node discovery. Presently hosts are cleared after control connection is started with contact points. Control connection queries the connected node and add_host to Session to populate the list.

Creating PR for review while still running integration and leak tests.
I wouldn't argue this.
I was getting by names originally, but I went with indexes because the query is right there, and I thought it was simple enough to see/maintain. :)
I think the row helper is a good idea though