Value of "opaque_index" in ACL session operational data is returned as a string instead if integer.

steps:
1. create ACL table
2. add ACL session to table:

{"classify-session": [

{ "match": "00:00:00:00:00:00:01:02:03:04:05:06:00:00:00:00", "hit_next": "permit", "advance": 1, "opaque_index": 1 }]}

3. Get classify session oper data:

{"classify-session:[

{ "match":"00:00:00:00:00:00:01:02:03:04:05:06:00:00:00:00", "hit_next":"permit", "advance":1, *"opaque_index":"1"* }]}