http: also refresh config on non-successful HTTP status

Change-Id: Ida0e4768bd300a4f11a09c8c66a2dbb062f7ff01
Reviewed-on: http://review.couchbase.org/33106
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Mark Nunberg <mnunberg@haskalah.org>