Add clone URLs to commit messages
Add clone URLs to commit messages

... seems useful enough that we ought to just do it by default.

Works fine on our server because the hostname is set right and the
path works out fine. Might work less well on servers configured
differently.

nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome,nmc-probe/emulab-nome