wizard: fix start a clean sync

The problem was that the backup function failed as we tried to
move  /home/xxx/ownCloud/  to /home/xxx/ownCloud/.oC_bak
The intention was to move it to /home/xxx/ownCloud.oC_bak

Issue #1989
Account: Fix cert save/restore from settings. #2160

(cherry picked from commit cc1121ef008d85f2142c6a2887e3ee196061e97f)
FolderMan: Fix startFromScratch logic. #1989

(cherry picked from commit 4566ca3127fa14f83b60a05411b0321f966c38a8)