barkeep: Some hacky features and expanded usage

* Add support for the ability to remove either multiple entries at once
  or, if no arguments supplied to `-r`, attempt to remove all found
  entries.  Essentially a complete wipe.

* Expanded the usage a bit to try make this clearer, `-r` is not
  designed to be used with other options, so I will add a warning,
  ignoring `-r` and working with whatever else the user supplied.

Generally not too happy with this situation but feel like this is
probably the most elegant solution I'm capable of at the moment.