Make operation_name public (#265)

Fixes #253.

juniper/src/http/mod.rs

@@ -33,6 +33,7 @@ impl<S> GraphQLRequest<S>
 where
     S: ScalarValue,
 {
+     /// Returns the `operation_name` associated with this request.
     fn operation_name(&self) -> Option<&str> {
         self.operation_name.as_ref().map(|oper_name| &**oper_name)
     }

juniper/test/graph_ql_request.rs

@@ -0,0 +1,10 @@
+extern crate juniper;
+
+#[test]
+fn pub_operation_name() {
+    use juniper::http::GraphQLRequest;
+
+    let request = GraphQLRequest::new("query".to_string(), Some("name".to_string()), None);
+
+    assert_eq!(request.operation_name(), Some("name"));
+}