Show spamreports icon based on number of spam reports

Added user preference "Minimum number of spamreports before showing spamreports icon" . This helps guarding against smart-asses that don't like a poster and then start reporting a post as spam even when it is not spam.
I had to run 'php upgrade-db' before I could store preference value.

I did not update the messages.po/mo files.. not sure if/how this needs to be done.