Add shard info (q,n) to db_info

[bdionne]

BugzID:11171

[kocolosk]

I dislike the name shard_info, as it could be interpreted as "information about this shard" when in fact it's information about the sharding topology of the entire database. But more importantly, the patch as written breaks replication compatibility with a number of versions of CouchDB. Can you remind me of which ones? To be safe I'd recommend adding n and q to the other sub-object until we explicitly drop compatibility with the older versions of CouchDB.

[bdionne]

hmm, I thought the compatibility issue related to the handling of atoms and was fixed in couchdb. Anyway it's easy enough and safer to put it into other.

I also agree the name is bogus, both here and in mem3.

[kocolosk]

It is fixed, but we can't retroactively fix versions of CouchDB that are already released ;)

[wohali]

This would save some headaches in support and help forgetful people. 👍