Random piece of data

[jacksoom]

In the previous version. the reveal data part is fixed. it also means that the path of the Merkle tree included proof is fixed. Which allows the publisher to easily cheat(the publisher only needs to ensure the correctness of the fixed reveal part).
So we introduce an external oracle machine here to ensure that the reveal part of data by users is random, and increase the number of the random data pieces. Publisher calls the contract Create item function. and the function will call an external oracle and generate three indpendent paths for the pieces data proof as publish input