SAN FRANCISCO – California’s ballot measure to legalize marijuana has a new friend: Facebook co-founder Sean Parker has given $100,000 to back the proposal.  Parker’s donation was reported in Proposition 19 campaign finance filings this week. And he’s not the first big Proposition 19 donor with ties to the social networking site. Facebook co-founder Dustin Moskovitz has made two donations totalling $70,000, including a $50,000 contribution last month.