Put `couch.uri` file in `dev` directory

My Couch seemed to have defaulted `uri_file` config value to
`/var/run/couchdb/couch.uri`, which is not writable by my user, thus
resulting in:

    [error] [<0.32.0>] Failed to write to URI file /var/run/couchdb/couch.uri: permission denied

Point `uri_file` to `dev` directory, next to rest of CouchDB files.