[stdlib-sig] Added dbm package to PEP 3108

So the dbm package as discussed on the old list has now been added to PEP 3108. I also updated the spreadsheet. I went with 'dbm.tools' as I liked Steve's arguments for it plus I just plain prefer it. =) I expect we will tackle the http package next when I (or someone else) starts off an email with suggested names (I have some already in the spreadsheet, but I should be doing real work instead of this =). -Brett