adding detection for Roku OS: https://en.wikipedia.org/wiki/Roku#Software

examples: http://www.webapps-online.com/online-tools/user-agent-strings/dv/brand798903/roku-dvp

note: The reason I added the test for Roku before all other tests is that Roku user agents might contain other tokens (like Windows), but Roku is still Roku.

src/parser-platforms.js

@@ -239,4 +239,16 @@ export default [
       };
     },
   },
+
+  /* Roku */
+  {
+    test(parser) {
+      return parser.getOSName(true) === 'roku';
+    },
+    describe() {
+      return {
+        type: PLATFORMS_MAP.tv,
+      };
+    },
+  },
 ];