Load entities from external JSON file

[pierrebeauguitte]

(Work in progress)
Instead of running a NER model in ePADD, load entities from a JSON file.

Syntax of file should be:

[
  {
    "message-id": "<abcdef1234567890>",
    "entities": [
      {
        "entity_group": "LOC",
        "score": 0.9995821118354797,
        "word": "Oslo",
        "start": 29,
        "end": 33
      }, ...
    ]
  }, ...
]

Location of JSON file has to be specified in epadd.properties file (a better solution is of course to choose the file via the "Import" web interface).

[jfarwer]

Thanks so much for the contribution, really appreciate your effort.