Fix a blocking queries bug

The lowest valid blocking query index is 1, but the API will return 0 if
there has yet to be an index set (no response). This in conjunction with
that 0 being stored as a string made the "fallback to 1" guard not work.

ui/app/services/watch-list.js

@@ -18,6 +18,6 @@ export default Service.extend({
   },
 
   setIndexFor(url, value) {
-    list[url] = value;
+    list[url] = +value;
   },
 });