[stdlib-sig] Added dbm package to PEP 3108

[Brett Cannon]

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