Add myself to AUTHORS and CONTRIBUTORS as requested wrt Fix #159.

AUTHORS

diff --git a/AUTHORS b/AUTHORS
index 6e7dd41..efb854a 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -22,6 +22,7 @@
 Matt Clarkson <mattyclarkson@gmail.com>
 Oleksandr Sochka <sasha.sochka@gmail.com>
 Paul Redmond <paul.redmond@gmail.com>
+Radoslav Yovchev <radoslav.tm@gmail.com>
 Shuo Chen <chenshuo@chenshuo.com>
 Yusuke Suzuki <utatane.tea@gmail.com>
 Dirac Research