Remove builds conditional on go1.7 since that is now guaranteed #2154

Old fallback code was deleted and the go1.7 style code inlined where
appropriate.

fs/rc/rc.go

@@ -9,6 +9,7 @@ package rc
 
 import (
 	"encoding/json"
+	"io"
 	"net/http"
 	"strings"
 
@@ -66,6 +67,13 @@ func (s *server) serve() {
 	s.srv.Wait()
 }
 
+// WriteJSON writes JSON in out to w
+func WriteJSON(w io.Writer, out Params) error {
+	enc := json.NewEncoder(w)
+	enc.SetIndent("", "\t")
+	return enc.Encode(out)
+}
+
 // handler reads incoming requests and dispatches them
 func (s *server) handler(w http.ResponseWriter, r *http.Request) {
 	path := strings.Trim(r.URL.Path, "/")