make 'tell everyone' message more specific for 'multi repository teams'.

[webervin]

Instead of Tell everyone to run 'git fetch --prune' to sync with this remote.
it should say Tell everyone to run 'git fetch --prune' to sync git-sweep. ('basename' for remote uri) or at least
Tell everyone to run git fetch --prune to sync https://github.com/arc90/git-sweep.git (full remote uri).

Currently one should 'manually' add repo name when passing on message to 'others',