[MERGE] show (possibly dotted) revnos in `bzr tags` (v2)

[Aaron Bentley]

Aaron Bentley has voted abstain.
Status is now: Waiting
Comment:
I don't think we should adopt a new output format for revisions.  If we 
enter --show-ids, then the output should be revision ids, not 
revno:revid listings.  For one thing, "0:asd;flkj" looks too much like 
"Arch:asd;flkj", which would be a rev-id.

For details, see: 
http://bundlebuggy.aaronbentley.com/request/%3C20070918115130.GA6478%40chistera.yi.org%3E