Make Cache\Scanner an emitter
manual backporting of OC\Files\Utils\Scanner to stable5
manual backporting of #4285
Remember the contructed OC\Files\Cache\* classes in OC\Files\Storage\Common
load authentication apps to get users from other backends like LDAP - THX @blizzz
Merge pull request #4317 from owncloud/backport-cli-scanner-stable5

Backport cli scanner to stable5