Counstruction metadata

[piotr-iohk]

Addressing #90.

$ curl -X POST 'http://localhost:3000/construction/metadata' \
-H 'Content-Type: application/json' \
-H 'Accept: application/json' \
-d '{
  "network_identifier": {
        "blockchain": "mina",
        "network": "testnet"
  },
  "options": {
        "sender": "B62qkUHaJUHERZuCHQhXCQ8xsGBqyYSgjQsKnKN5HhSJecakuJ4pYyk",
        "receiver": "B62qoDWfBZUxKpaoQCoFqr12wkaY84FrhxXNXzgBkMUi2Tz4K8kBDiv",
        "token_id": "1",
        "valid_until": "200000",
        "memo": "hello"
  }
}'|jq
....
{
  "metadata": {
    "memo": "hello",
    "nonce": "3",
    "receiver": "B62qoDWfBZUxKpaoQCoFqr12wkaY84FrhxXNXzgBkMUi2Tz4K8kBDiv",
    "sender": "B62qkUHaJUHERZuCHQhXCQ8xsGBqyYSgjQsKnKN5HhSJecakuJ4pYyk",
    "token_id": "1",
    "valid_until": "200000"
  },
  "suggested_fee": [
    {
      "value": "1000000",
      "currency": {
        "symbol": "MINA",
        "decimals": 9
      },
      "metadata": {
        "minimum_fee": {
          "currency": {
            "decimals": 9,
            "symbol": "MINA"
          },
          "value": "1000000"
        }
      }
    }
  ]
}