Ledger connection timeout

[bartekn]

It looks like Ledger connection timeouts if payment is not confirmed quickly. To reproduce:

1. Login using Ledger device.
2. Send 1 XLM to yourself.
3. Wait for 60 seconds in the Ledger device confirmation screen.
4. Confirm transaction in the Ledger device.

At this point, nothing happens and transaction is not signed.

[vcarl]

The bug here is that the timeout fails silently. We should have some kind of message indicating that the transaction has failed to submit and why.