Add comment support

[markberger]

It would be nice to be able to refer to a specific comment on a ticket

[daira]

On #tahoe-lafs:

(2015-04-13 20:53:05) daira1: also see https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2400#comment:4
(2015-04-13 20:53:51) igor-: #2400#comment:4
(2015-04-13 20:53:52) tahoe-bot: #2400 (OpenSSL.crypto.Error (unknown message digest algorithm) when starting a node, using OpenSSL 1.0.1k-fips)
(2015-04-13 20:53:52) tahoe-bot: https://tahoe-lafs.org/trac/tahoe-lafs/ticket/2400
(2015-04-13 20:54:05) igor-: hahaha.
(2015-04-13 20:55:48) daira1: igor-: https://github.com/markberger/tally/issues/10