packaging: setup: accept configuration by default

Previously user was required to answer yes for approving
configuration preview. Now user can just hit enter.

Change-Id: I960df6c971013aa08726a64bd22425a3dc27fe65
Bug-Url: https://bugzilla.redhat.com/1107772
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>