(Refactor) Avoid decoding empty claim

[phahulin]

• What is it? (leave one option)
  • (Refactor) proposal (i.e. no new features or updates, just code optimization/library updates)

In function userAddressInfo

https://github.com/poanetwork/poa-popa/blob/master/blockchain/contracts/ProofOfPhysicalAddress.sol#L251-L262

it's suggested to use the following check to avoid decoding 0 claim:

bytes32 claim = registry.getClaim(
   address(this),
   wallet,
   users[wallet].physicalAddresses[addressIndex].keccakIdentifier);
return (
   users[wallet].physicalAddresses[addressIndex].name,
   users[wallet].physicalAddresses[addressIndex].creationBlock,
   uint256(claim) != 0 ? PhysicalAddressClaim.decodeConfirmation(claim) : 0,
   users[wallet].physicalAddresses[addressIndex].keccakIdentifier
);