New version 1.7.1 hard coded

Stable release requires modifications: don't show version and generation time in footer, don't check the upgrade feed, don't die on sql errors.

Missed version update in tools/create_listing_file.php

git-svn-id: http://piwigo.org/svn/tags/release-1_7_1@2196 68402e56-0260-453c-a942-63ccdbb3a9ee