Invalid source and timestamp in RMC position and GGA

[tkurki]

RMC is producing invalid delta for position. The source and timestamp are incorrectly in value:

`$GPRMC,200309.00,A,5310.81264,N,00525.70578,E,0.009,,160414,,,D*73``
=>

{
  "context": "vessels.4193B873",
  "updates": [
    {
      "source": {},
      "timestamp": "2016-12-29T06:25:33.911Z",
      "values": [
        {
          "path": "navigation.position",
          "value": {
            "source": {
              "type": "NMEA0183",
              "sentence": "RMC",
              "label": "signalk-parser-nmea0183",
              "talker": "GP"
            },
            "timestamp": "2014-05-16T20:03:09.000Z",
            "longitude": 5.428429666666666,
            "latitude": 53.18021066666667
          }
        }
      ]
    }
  ]
}

[tkurki]

Same thing in GGA:

$GPGGA,200309.00,5310.81264,N,00525.70578,E,2,09,1.13,2.7,M,45.7,M,,0000*5F
=>

{
  "context": "vessels.2DE86D73",
  "updates": [
    {
      "source": {},
      "timestamp": "2016-12-29T06:28:14.753Z",
      "values": [
        {
          "path": "navigation.position",
          "value": {
            "source": {
              "type": "NMEA0183",
              "sentence": "GGA",
              "label": "signalk-parser-nmea0183",
              "talker": "GP"
            },
            "timestamp": "2016-12-29T20:03:00.000Z",
            "longitude": 5.428429666666666,
            "latitude": 53.18021066666667
          }
        }
      ]
    }
  ]
}
{
  "context": "vessels.2DE86D73",
  "updates": [
    {
      "source": {},
      "timestamp": "2016-12-29T06:28:14.755Z",
      "values": [
        {
          "path": "navigation.gnss",
          "value": {
            "source": {
              "type": "NMEA0183",
              "sentence": "GGA",
              "label": "signalk-parser-nmea0183",
              "talker": "GP"
            },
            "timestamp": "2016-12-29T20:03:00.000Z",
            "quality": 2,
            "satellites": 9,
            "antennaAltitude": 2,
            "horizontalDilution": 1,
            "geoidalSeparation": 45,
            "differentialAge": 0,
            "differentialReference": 0
          }
        }
      ]
    }
  ]
}

[fabdrol]

current master version also produces too many delta's - see comment on #77. It's fixed in the version on development branch.