Feature/1.1.0 beta 4

[katat]

• Upgrade SDK to 2.3 and integrate the off-chain balance sync check.

• Even now it is integrated with SDK's off-chain sync check, I realised the time blocker is still needed to be in place because:

  1. The off-chain balance sync check is only effective when the new settlement transaction is confirmed on-chain.
  2. The transaction confirmation could take a few minutes, in which the balance sync check won't be able to prevent new payments.

So we will need two types of sync checkings. The one at the front end to check if the transaction is either mining or mined or failed. The other one is to check with the backend and the contracts to see if the off-chain balance is in sync or not.

At the moment, the time block is a simple form of checking for the front end side, as it is having a constant time for blocking. The optimal alternative would be persisting the transaction hash in localstorage, so UI can check the status of the new settlement transaction even after restarted hubii core.

[katat]

Updated to deprecate the time block, and check the mining status of the settlement transactions instead. The payment blocking now should be more reliable based on the checkings against both the statuses of transaction mining and the off-chain balance synchronisation.