Silence redundant logging to stdout/stderr

Instead print log filename to stdout during startup.

CouchDB already logs everything to /var/log/couchdb/couch.log.
The stdout/stderr redundantly floods /var/log/messages.
This temporary hack was suggested by rnewson in #couchdb.
https://issues.apache.org/jira/browse/COUCHDB-2264
Related issue
Allow passing directories as the config sources

We should allow passing the entire directories as the config sources. In
this case CouchDB will traverse the given directories and load every
*.ini file found.

E.g.

"... -couch_ini /etc/couchdb/default.d/ /etc/couchdb/local.d/ /path/to/extra/couchdb/default.ini /path/to/extra/couchdb/local.ini ..."

Signed-off-by: Peter Lemenkov <lemenkov@gmail.com>