Small fix changing text property to string. Fixes Issue 46.

Reviewed in https://codereview.appspot.com/8427044/
diff --git a/endpoints_proto_datastore/ndb/utils.py b/endpoints_proto_datastore/ndb/utils.py
index feed42b..4111092 100644
--- a/endpoints_proto_datastore/ndb/utils.py
+++ b/endpoints_proto_datastore/ndb/utils.py
@@ -63,7 +63,7 @@
     ndb.PickleProperty: messages.BytesField,
     ndb.Property: RaiseNotImplementedMethod(ndb.Property),
     ndb.StringProperty: messages.StringField,
-    ndb.TextProperty: messages.BytesField,  # No concept of compressed here
+    ndb.TextProperty: messages.StringField,  # No concept of compressed here
     ndb.TimeProperty: messages.StringField,
 }