to a "constants" class

This patch was automatically generated as part of the following inspection:
https://scrutinizer-ci.com/g/owncloud/core/inspections/cdfecc4e-a37e-4233-8025-f0d7252a8720

Enabled analysis tools:
 - PHP Analyzer
 - JSHint
 - PHP Copy/Paste Detector
 - PHP PDepend

Issue #7111

add a optional parameter to skip check for expired files, this is necessary to find out to whom a file was shared after it was expired.

Use a DateTime object and have conversion handled by Doctrine instead of using
a date string with a fixed format.

pass the name of the item source from the browser to the server - no need to get the data via complicated db queries

fixe #2827

refs #4883

 * http/response.php
 * config.php
 * response.php
 * files.php
 * idbconnection.php
 * app.php
 * user.php
 * template.php
 * share.php
 * db.php
 * icache.php & il10n.php