Move over to commands

[mjpitz]

Right now, there is a single command gitfs. This starts a file system server on a designated mountpoint. Ideally, we want to support a variety of commands, not just starting the server. For example:

• start would perform the same functionality as gitfs does today. If no command is provided, then this command should be invoked by default.
• stop would force the file system server to unmount. Note, that using fuse.Unmount will not work as it requires all references to the underlying files to be released (i.e all terminal windows and applications closed). I've been able to do this on osx and linux using the sudo umount -f ${mountpoint}
• config would behave a lot like git-config, making it possible to modify properties without needing to modify the files directly.

Each of these commands should be implemented as their own ticket.