This reverts commit 6a1a4880.

use flock instead of just checking if there is a file to prevent deadlocks when the process crashed or the unlink wasnt done

move cron.lock into top directory to prevent external storage issues

use tmp directory lock file

use new config interface

incorporate #13770

add dots

maintain deprecated \OC::$session when getting or setting the session via the server container or UserSession

restore order os OC::$session and OC::$CLI

remove unneded initialization of dummy session

write back session when $useCustomSession is true

log warning when deprecated app is used

[error] 4461#0: *186285 FastCGI sent in stderr: "PHP message
: PHP Fatal error:  Call to a member function execute() on null in /var/www/ownc
loud/cron.php on line 125" while reading response header from upstream, client:
217.13.183.252, server: cloud.mycloud.com, request: "GET /cron.php HTTP/1.1", upstre
am: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "cloud.mycloud.com", referrer: "
https://cloud.mycloud.com/"

Fixes #2012

Typo in comment "feature" => "future"

now should work with temp files too

respect coding style

Add "cron.php" for background jobs. It is named cron.php because more people will recognize the purpose of the file then.