add a gittip link to AUTHORS.md
add a gittip link to AUTHORS.md

WillianPaiva/1flow,WillianPaiva/1flow,1flow/1flow,WillianPaiva/1flow,1flow/1flow,1flow/1flow,1flow/1flow,WillianPaiva/1flow,WillianPaiva/1flow,1flow/1flow