Fix commentdata json output format

[josx]

Right now when writing json file on commentdata command, comments are not separated by comma, just by enter.

With this fix the output data is valid json format.

Replace example:

{ "Comments":[
{"post_id": "", "user_id": "", "username": "", "comment": ""}
{"post_id": "", "user_id": "", "username": "", "comment": ""},
]}

with

{ "Comments":[
{"post_id": "", "user_id": "", "username": "", "comment": ""},
{"post_id": "", "user_id": "", "username": "", "comment": ""}
]}