Update LICENSE.txt year to 2013

https://trello.com/c/Iq5CJmIh/

Update our open source license copyright to the current year.

Change-Id: I57f9c5956d5634aa84edff9289931c3b102192cf
Merge branch 'master' of ssh://review.motechproject.org:29418/platform-campaigns
Merge branch 'master' of ssh://review.motechproject.org:29418/platform-campaigns
[maven-release-plugin] prepare branch 0.21.X

Change-Id: I95db771931952749ee34783b74456ce47e47997b