This reverts commit d2d71c87.
which was accidentally commited

It was not possible to download a file called "true" or "false" (caseinsensitive) when clicking the link "download" due to the result of json_decode().
Both cases are now implicitly checked.

Hotfix provided by Herbert Pophal

This will help not to accidentially push private data and enable testing on our ci server.

use pre_setPassword hook to update the encryption keys if the back-end doesn't support password change; improved output to let the admin know what happened

add a hint that the admin can recover your files; Don't let the user change the recovery settings if no private key is set