pimd: Added json to 'show ip igmp group'

pimd: Added json to 'show ip igmp group'

Signed-off-by: Daniel Walton <dwalton@cumulusnetworks.com>
root@superm-redxp-05[quagga-pim]# vtysh -c 'show ip igmp group'
Interface Address         Group           Mode Timer    Srcs V Uptime
br1       20.0.13.1       230.40.40.1     EXCL 00:03:24    1 3 00:01:28
root@superm-redxp-05[quagga-pim]#
root@superm-redxp-05[quagga-pim]#
root@superm-redxp-05[quagga-pim]# vtysh -c 'show ip igmp group json' |
python -m json.tool
{
    "br1": {
        "230.40.40.1": {
            "group": "230.40.40.1",
            "mode": "EXCLUDE",
            "source": "20.0.13.1",
            "sourcesCount": 1,
            "timer": "00:03:23",
            "uptime": "00:01:30",
            "version": 3
        },
        "address": "20.0.13.1",
        "flagBroadcast": true,
        "flagMulticast": true,
        "index": 96,
        "lanDelayEnabled": true,
        "name": "br1",
        "state": "up"
    }
}
root@superm-redxp-05[quagga-pim]#