add directory listing functionality to bup_storage
add directory listing functionality to bup_storage

tscholl2/smc,DrXyzzy/smc,sagemathinc/smc,sagemathinc/smc,DrXyzzy/smc,sagemathinc/smc,tscholl2/smc,DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc,tscholl2/smc,tscholl2/smc