Bump version to 13.1.6-dev
Bump version to 13.1.6-dev

eXcomm/gratipay.com,gratipay/gratipay.com,studio666/gratipay.com,studio666/gratipay.com,eXcomm/gratipay.com,studio666/gratipay.com,studio666/gratipay.com,mccolgst/www.gittip.com,mccolgst/www.gittip.com,gratipay/gratipay.com,eXcomm/gratipay.com,mccolgst/www.gittip.com,gratipay/gratipay.com,mccolgst/www.gittip.com,eXcomm/gratipay.com,gratipay/gratipay.com