Update contributors list -- great community!

Author: Dana Powers

AUTHORS.md

@@ -1,16 +1,19 @@
 # Contributors
 
-Top 10 contributors, listed by contribution. See https://github.com/mumrah/kafka-python/graphs/contributors for the full list
+Top contributors, listed by contribution. See https://github.com/mumrah/kafka-python/graphs/contributors for the full list
 
 * David Arthur, [@mumrah](https://github.com/mumrah)
 * Dana Powers, [@dpkp](https://github.com/dpkp)
 * Mahendra M, [@mahendra](https://github.com/mahendra)
 * Mark Roberts, [@wizzat](https://github.com/wizzat)
 * Omar, [@rdiomar](https://github.com/rdiomar) - RIP, Omar. 2014
+* Viktor Shlapakov, [@vshlapakov](https://github.com/vshlapakov)
 * Bruno Renié, [@brutasse](https://github.com/brutasse)
 * Marc Labbé, [@mrtheb](https://github.com/mrtheb)
+* John Anderson, [@sontek](https://github.com/sontek)
 * Ivan Pouzyrevsky, [@sandello](https://github.com/sandello)
 * Thomas Dimson, [@cosbynator](https://github.com/cosbynator)
-* Zack Dever, [@zever](https://github.com/zever)
+* Alex Couture-Beil, [@alexcb](https://github.com/alexcb)
+* Zack Dever, [@zackdever](https://github.com/zackdever)
 
 Thanks to all who have contributed!