Feature/test delete

[matthewpeterkort]

A query like:

query($filter: JSON){
  observation(filter:$filter first: 10000) {
    id
    identifier {
      value
    }
    auth_resource_path
    focus {
      ... on ConditionType {
        id
        identifier {
          value
        }
      }
    }
  }
}

with filter

{
  "filter": {
    ">": {
      "Condition.onsetAge.value": "25000"
    }
  }
}

working on development with this PR