Add missing imports to NAMESPACE and DESCRIPTION

Change-Id: Id03a13e5da18107dd486bbc72b1d47c71aff00ac
diff --git a/DESCRIPTION b/DESCRIPTION
index 91bbd45..a554477 100644
--- a/DESCRIPTION
+++ b/DESCRIPTION
@@ -9,3 +9,7 @@
 Encoding: UTF-8
 LazyData: false
 RoxygenNote: 6.1.1
+Imports:
+    curl,
+    jsonlite,
+    utils