Add Datasets Endpoints

[PGijsbers]

Add the following dataset endpoints:

GET

• GET /data/{id}  #7

• GET /data/list/{filters} #8
  List and filter datasets

• GET /data/features/{id} #9
  Get data features

• GET /data/qualities/{id} #10
  Get data qualities

• GET /data/qualities/list #11
  List all data qualities

• GET /data/unprocessed/{data_engine_id}/{order} #12
  Get a list of unprocessed datasets

DELETE

• DELETE /data/{id} #13
  /data/{id}
  Delete dataset

POST

• POST /data #14
  Upload dataset

• POST /data/status/update/ #15
  Change the status of a dataset

• POST /data/features #16
  Upload dataset feature description

• POST /data/qualities #17
  Upload dataset qualities

• POST /data/qualities/unprocessed/{data_engine_id}/{order} #18
  Get a list of datasets with unprocessed qualities

• POST /data/tag #19
  Tag a dataset

• POST /data/untag #20
  Untag a dataset