Added credits to readme for karlhaas

Author: ashokfernandez

README.md

@@ -71,6 +71,8 @@ The screenshot below show angular-selector in action with all options enabled:
 
 [Tom Grooffer](https://github.com/tomgrooffer) for fixing a crash with JSTZ
 
+[karlhass](https://github.com/karlhaas) for fixing a crash when two instances were present on the same page
+
 #### Attributions
 Inspired by [angular-timezone-select](https://github.com/alexcheng1982/angular-timezone-select) from [alexcheng1982](https://github.com/alexcheng1982).