drop OC_Preferences::getUsers and getApps
Merge pull request #12336 from owncloud/drop-getApps-getUsers

drop OC_Preferences::getUsers and getApps
Revert "drop OC_Preferences::getUsers and getApps"

This reverts commit 09fd34eed908203674721af86ce889bfd0a0ef8d.
update grammar

Suggested by mnestis on Transifex.
Merge pull request #12344 from owncloud/fixstypo

update grammar
[tx-robot] updated from transifex
migrated OC_Preferences::deleteAppFromAllUsers to deleteApp in \OCP\IConfig