basic site notifications
adds access override to create site notifications during cron job
Removing trailing white chars
Changed upper case occurrences of NULL/TRUE/FALSE to lower case for /engine/ except deprecated* and upgrades
Merge pull request #5595 from Srokap/develop2

Coding standards fix for trailing spaces and lowercasing keywords since we mostly follow PSR-2 now
made use of metadata consistent in function naming (backward compatible since PHP does not care about case)
Added summary message to notifications
added actions menu and delete
added ajax for removing notifications
Merge pull request #5461 from cash/site_notifications

Site notifications plugin
Fixes #5590 do not try to login a user that has been disabled