Add to contributers and authors (#4263)

CONTRIBUTORS.txt

@@ -250,3 +250,4 @@ Kxrr, 2017/08/18
 Mads Jensen, 2017/08/20
 Markus Kaiserswerth, 2017/08/30
 Andrew Wong, 2017/09/07
+Arpan Shah, 2017/09/12

docs/AUTHORS.txt

@@ -14,6 +14,7 @@ Allan Caffee <allan.caffee@gmail.com>
 Andrew McFague <amcfague@wgen.net>
 Andrew Watts <andrewwatts@gmail.com>
 Armin Ronacher <armin.ronacher@active-4.com>
+Arpan Shah <arpanshah29@gmail.com>
 Ask Solem <ask@celeryproject.org>
 Augusto Becciu <augusto@becciu.org>
 Balachandran C <balachandran.c@gramvaani.org>