add @shiwano and update changelog

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2015-10-07
+
+* Add broadcast methods for binary messages.
+
 ## 2015-09-03
 
 * Add `Close` method to melody instance.

README.md

@@ -67,6 +67,10 @@ func main() {
 
 ## [Documentation](https://godoc.org/github.com/olahol/melody)
 
+## Contributors
+
+* Ola Holmström (@olahol)
+* Shogo Iwano (@shiwano)
 
 ## FAQ