[CS-5475] Manage background jobs via backend

updated documentation to install Newscoop on ubuntu 14.04

dont add cron job when it already exist in database

flush conjobs entities

added upgrade script to move old cron jobs to database and activate only master one

fix autgeneration

use clear em for sheduler

improved cronjobs script

added sorting to table with background jobs

added method to remove cron jobs

added php to master cron job command
added 302 status code in user login API when _target_path param is given

added cron job schedule in title attribute for nextRunDate
Merge pull request #775 from takeit/master

[CS-5475] Manage background jobs via backend