Bugfix: Run() fails for queries, add MarshalJSON()

The `Run()` method on the `QueryRequest` type would fail, since it would
encode the _inner_ body of the query to JSON and not the complete, outer
body (i.e. including the "body: {}" portion).

The commit also adds `MarshalJSON()` methods to both `QueryRequest` and
`AggregationRequest`, allowing them to implement the `json.Marshaller`
interface, and providing easier debugging of the library. A test
skeleton for this is also added.

queries_test.go

@@ -4,7 +4,7 @@ import (
 	"testing"
 )
 
-func TestQueries(t *testing.T) {
+func TestQueryMaps(t *testing.T) {
 	runMapTests(t, []mapTest{
 		{
 			"a simple match_all query",
@@ -66,3 +66,17 @@ func TestQueries(t *testing.T) {
 		},
 	})
 }
+
+func TestQueryJSONs(t *testing.T) {
+	runJSONTests(t, []jsonTest{
+		{
+			"simple query",
+			Query(
+				Bool().
+					Must(Term("account_id", "bla")),
+			),
+			`{"query":{"bool":{"must":[{"term":{"account_id":{"value":"bla"}}}]}}}`,
+			nil,
+		},
+	})
+}