Bumped version to 2.3.1
Bumped version to 2.3.1

mibcadet/momentjs.com,moment/momentjs.com,moment/momentjs.com,peterbecker/momentjs.com,jeyraof/momentjs.com,A----/momentjs.com,A----/momentjs.com,interactivellama/momentjs.com,maximveksler/momentjs.com,peterbecker/momentjs.com,bbodenmiller/momentjs.com,hulbert/momentjs.com