Split the commands and change the naming.
* Tracking a repo is now called "seeding"
* Tracking a peer is now called "following"
In this commit, we don't change most of the internal code, only the
user-facing part.
When tracking a repository with the `--fetch` option, we run a fetch
once the tracking is done.
When tracking nodes, we don't accept the `--fetch` flag, as there may
not be a repository to fetch.
cloudhead
Michail Zampetakis
Alexis Sellier
Fintan Halpenny