CPaster: Fix usage of kdepaster

Network protocol changed to use https now and xml api is no more
working - switched to json api.

Task-number: QTCREATORBUG-13580
Change-Id: I9d2b4738db1130b6f123b354095fbb4d89bf9855
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Robert Loehning <robert.loehning@theqtcompany.com>
Reviewed-by: Eike Ziller <eike.ziller@theqtcompany.com>