Pass back isLoading to scoped-slot (#218)

* Pass back `isLoading` to scoped-slot

Right now `loading` is only set when a result is received, not when the request is sent. Using `watchLoading`, we can pass the loading state from when the request is sent.

* Use $apolloData.loading

We can simply use the $apolloData.loading property to get the current loading state of the query.

Author: Ben52

src/components/ApolloQuery.js

@@ -165,6 +165,7 @@ export default {
     let result = this.$scopedSlots.default({
       result: this.result,
       query: this.$apollo.queries.query,
+      isLoading: this.$apolloData.loading,
     })
     if (Array.isArray(result)) {
       result = result.concat(this.$slots.default)