combine metadata, time series and trajectory data

[kok-foong]

Previously the ConfigEntry class was written such that an instance can only contain "meta + time", or "trajectory" only, this work will make it possible to have something like

{
    "id": "1",
    "class": "http://class_iri",
    "meta": {...}            
    "time": {...},
    "trajectory": [...]
}

instead of having to have something like

{
    "id": "1",
    "class": "http://class_iri",
    "meta": {...}            
    "time": {...}
},
{
    "id": "2",
    "class": "http://class_iri",
    "trajectory": {...}
}

The "trajectory" data is also changed to an array instead of an object