[issue1863] Implement 'hammer volume-list' subcommand

[Matthew Dillon]

:git format-patch -1 automatically added the 0001- prefix, since I re-based my 
:patch and made it appear on top of the commit history.
:
:Sorry for the inconvenience.
:
:Speaking of fetch(1), could we make it automatically append an increasing 
:counter if the file to be fetched already exists on disk ?
:
:Stathis

    I'd rather not.  Many programs rely on fetch to operate just like it
    does now.

					-Matt
					Matthew Dillon 
					<dillon at backplane.com>