packaging: setup: generate answerfile readable by user only

fix file mode of previous stored answer files at state.

Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1028748
Change-Id: I3c1ca00b7a56216d7051c7625c5e983d422caab9
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>