Connect all the Things

This release adds the wharfer network (sub-)commands and flags needed for simple bridged networks.

For example one can create two containers which can talk to each other using the names alice and bob with the following commands

(Term 0) # wharfer network create testnet
(Term 0) # wharfer run -it --network testnet --network-alias alice busybox
(Term 1) # wharfer run -it --network testnet --network-alias bob busybox

(Term 0) # ping bob
(Term 1) # ping alice

Also the username is now automatically prepended for wharfer logs, wharfer rm and wharfer kill. It is only prepended if it isn't already specified so using the full name still works.