Tests for node and edge details

[georgiana-b]

We need endpoints to retrieve details for network nodes, clusters and edges. All these values will be calculated on the aggregated winning bids of the parts involved filtered by the query of the network:

• GET /network/:id/nodes/:id
  • total income
  • average competition
  • percent of data missing
  • type
  • actors (the correspondiing actor id, an array if the node is cluster)
  • nodes (in case this is a cluster)
  • list of winning bids exchanged with the following attrs for each bid:
    • lot title
    • tender title
    • bid value
    • number of bids for the lot
    • award date
    • bidders (nodes)
      • id
      • label
      • nodes
      • actors
    • buyers (nodes
• GET /network/:id:/clusters/:id
  • same as above
• GET /network/:id/edges/:id
  • total money exhanged
  • average competition
  • percent of data missing
  • bids exchanged - with attrs as above

[georgiana-b]

These have been developed in #77 but due to time constraint have not been tested so I renamed the issue to reflect that.