Change prettier config

Less brutal trailing comma's to support mainstream browsers in non minified build.
Fixes angular-ui/ui-router#3696

Author: Nickman87

.prettierrc.json

@@ -1,5 +1,5 @@
 {
   "singleQuote": true,
-  "trailingComma": "all",
+  "trailingComma": "es5",
   "printWidth": 120
 }