added Table.update_ids method

@wasade or @ElDeveloper, can one of you review this one? I haven't contributed to biom in a while - let me know if I'm doing anything wrong. The codebase is looking really nice, btw! 
Note that you can append ``?w=0`` to the url of the page when doing code review to hide whitespace changes ([for example](https://github.com/biocore/biom-format/pull/536/files?w=0))