[api] Get broadcasted tx for op

[cbermudez97]

Original Issue: fibercrypto/skyxcommons#21
[GET] /api/transactions/broadcast/single/{operationId}

Should return broadcasted transaction by the operationId . All transactions with single input and output, that were broadcasted by the [POST] /api/transactions/broadcast should be available here.

{
// Operation ID.
“operationId”: “guid”,
// State of the transaction
// enum values:
// -  inProgress : transaction is being in-progress
// -  completed : transaction is completed for sure
// -  failed : transaction is failed, if applicable for the
//     particular blockchain
“state”: “enum”,
 // Transaction moment as ISO 8601 in UTC
“timestamp”: “datetime”,
//  Amount without fee.
// Is integer as string, aligned to the asset accuracy.
// Actual value can be calculated as
// x = sourceAmount * (10 ^ asset.Accuracy)
// Should be non empty if the  state is  Completed
“amount”: “string”,
//  Fee should be zero if the  state is  Completed
    “fee”: “string”,
   // Transaction hash as base64 string.
   // Can be empty
// Should be non empty if the  state is  Completed
    “hash”: “string”,
// Error description
// Can be empty
// Should be non empty if the  state is  Error
“error”: “string”,
// Error code.
// Can be empty.
// Should be non empty if the state is Failed.
// enum values:
// -  unknown : any error that does not fit another codes.
// -  amountIsTooSmall : amount is too small to execute
// transaction
// -  notEnoughBalance : transaction can’t be executed due
// to balance insufficiency on the source address.
// Should be non empty if the  state is  Error
“errorCode”: “enum”,
// Incremental ID of the moment, when the transaction
// state changing is detected. It should be the same
// sequence as for block in the  [GET] /api/balances
// response. In other words, block number/height.
    “block”: integer64
}

Errors:

* `204 No content`  - specified transaction not found