SimpleGraphQLServlet: Add listeners to builder (#57)

* Fix problem: When GraphQLServletListener is added and it throw an error, the request continues without any effect.

* Add listeners to Builder in SimpleGraphQLServlet

* Return to master original version

* Return to master original version

* Return to master original version

Author: fnovoa10

src/main/java/graphql/servlet/SimpleGraphQLServlet.java

@@ -180,6 +180,11 @@ public Builder withPreparsedDocumentProvider(PreparsedDocumentProvider provider)
             return this;
         }
 
+        public Builder withListeners(List<GraphQLServletListener> listeners) {
+            this.listeners = listeners;
+            return this;
+        }
+
         public SimpleGraphQLServlet build() {
             return new SimpleGraphQLServlet(this);
         }