Fetch comand to upload gevent data and logs

Fetch command should download also the "gevent_data" and "logs" to be joined in description.json

Now the meg fetch command of a GEvent creates a file description.json with only the data need to recreate the events we need to add to entry at the dictionary to have the logs and the gevent data:

{
    "id": "G1051880",
    "source": "playground",
    "pipeline": "gstlal",
    "group": "CBC",
    "search": "EarlyWarning",
    "offline": false,
    "gpstime": 1368150075.115275,
    "reporting_latency": 5.426515,
    "uploads": [
        {"message": "Original Data","tags": [], "filename": "coinc.xml,0","delay": 0.0},
        { ...... },
        { ...... }
       ],
    "gevent_data": {...},
    "logs": {...}
}