Removed test test_register_invalid_transfer
Removed test test_register_invalid_transfer

The test was made for DirectTransfers with a secret field. It was the
case that direct transfers could have a secret field and that the secret
was registered *before* the transfer message was fully validated.

Since then direct transfers don't have the secret field anymore, so the
incosistent state is not reachable anymore.

- The test was introduced by: baad50952173ef75b681ad6de09d9e31f0f9b54e
- The bug was fixed by: 9d341acb885360fb20d7a33adb6081f83cc59c84
- Direct transfer's secret field removed by: 05e79d9eda8f850a019893432ba12d78c2de07bf

hackaugusto/raiden,hackaugusto/raiden