hkjc changed to use json, instead of XML

Due to the change of the hkjc.com backend, there maybe some errors in the last few days.

Working hard to fix the problem.

Previously, hkjc had been using xml to present the data. and now changed to JSON.

It's more clear in the json version. But need to modify the fetch method.

Here is the link to get the json:
http://bet.hkjc.com/football/getJSON.aspx?jsontype=odds_allodds.aspx&mat...
http://bet.hkjc.com/football/getJSON.aspx?jsontype=index.aspx