Throw Error instead of redirect

We must not redirect in a Cronjob.
Comment added
Fixed $variable name
Changelog updated
Analytics config fixed to work for cronjob
Set class exists back to one rule, as it should
Merging master
Merge branch 'bugfix-cronjob' of github.com:jeroendesloovere/forkcms into jeroendesloovere-bugfix-cronjob

Conflicts:
	CHANGELOG.md
	src/Backend/Core/Engine/Cronjob.php
Merge branch 'jeroendesloovere-bugfix-cronjob'