review post: Add -ask_once and fix minor issues
review post: Add -ask_once and fix minor issues

Added -ask_once flag, which makes review post ask for the story ID only
once. That selected ID is then used for all missing Story-Id tags. This
can make review post much less annoying in case the user knows he or she
is posting reviews for one particular story.

Change-Id: a655706b42
Story-Id: SF-15

salsaflow/salsaflow,salsaflow/salsaflow