list_to_existing_atom is too restrictive as used by couch_rep

We'd like to additional information to db_info in BigCouch, such as the Q and N constants for a given database. This causes replication to fail when replicating from BigCouch to CouchDB due to the use of list_to_existing_atom in couch_rep:dbinfo(...

The claim is that list_to_atom pollutes the atoms table, however superficial testing indicates this is not the case, list_to_atom when called repeatedly seems to work fine. If this is true then consider reverting list_to_existing_atom back to list_to_atom.